Table of Contents

Bill of Materials

Everything the column is made of, with sourcing and a costed total. Links last checked 2026-09-03 — see Cost and sourcing status for what is verified and what is still an estimate. The build order, drawings and pin table live on the dashboard's Build page (/build).

What this is

A single rigid square-section acrylic column, stacked bottom to top. Three load-bearing risers carry the outworld down to the nest, which frees the fourth face of the electronics bay to open as a drawer.

                    lid, vented, Fluon rim
             ,-------------------------------.
             |          OUTWORLD             |   frosted ring-window around
             |     o     ~~~~                |   each riser mouth
        ,----|===============================|----,   <- outworld floor plate, 10 in sq
        ||   |     BAY ENCLOSURE  [drawer]  >|>   ||   RGB rings shine UP through the floor
        ||   |     5.25 in sq, no load       |    ||   the drawer comes out this face
        `----|===============================|----'   <- nest ceiling plate, 10 in sq
        ^^   |:::::::::::::::::::::::::::::::|   ^^
        ||   |::   YTONG NEST CORE         ::|   ||    opaque sleeve lifts off to view
        ||   |::   two slabs, back to back ::|   ||
        ||   |::   [131 mL reservoir]      ::|   ||    wicks; never pumped into
             |_______________________________|
       =========================================
       |  ballasted base -- pumps + supply jar  |
       |______________ moat tray _______________|

    ^^ two of the three risers; the third is on the far face

Nothing is free-standing, nothing is push-fit, and there is no gate.

The load path

The outworld, its substrate and the lid come to about five pounds, and they sit above a bay that has to be open on one side. Everything about the middle of the column follows from that.

Load leaves the outworld floor plate — a 10 in square that overhangs the column by ¾ in on every side — through three ¾ in OD acrylic risers on the midlines of three faces, and through a portal frame of two stiles and a header on the fourth. It arrives at an identical nest ceiling plate and passes into the nest walls and the base.

The plate overhang is not decoration: it is the land the riser collars bear on, and the rebate the outworld gasket clamps into.

The bay enclosure carries nothing. It is a 5¼ in box standing between the plates — a waist inside the column line — and its only job is keeping light and dust off the electronics. That is exactly why one of its four faces can be a hole. Three faces are closed panels with a riser standing in the step outside each; the fourth is the drawer, framed by the portal.

Three supports on a four-sided plate put the resultant off-axis, which is what the portal frame is for: its stiles take the fourth quarter of the load, so the plate is supported at four points and the drawer slides through a frame already carrying its share.

The riser-through-plate joint

The joint that carries both the load and the containment. It is a weld, not a fitting:

        collar, 2 in OD (solvent-welded)
                 |
    ============[|]============    bay plate, ¼ in, drilled to tube OD
                 |
        collar, 2 in OD (solvent-welded)
                 |
             riser tube, ¾ in OD, ½ in bore

Drill the plate to the tube's outside diameter, slide the tube through, then solvent-weld an acrylic collar against each face and fillet with Weld-On 16. Solvent welding chemically fuses the parts into one piece of acrylic — no gasket to compress, no friction fit to work loose — and the collars turn the joint into a bearing surface rather than a hole the tube happens to sit in. About 5.4 in² of welded annulus per plate per riser — two 2 in collars at 2.7 in² each — against a service load under two pounds each.

Weld this assembly flat on the bench, both plates clamped parallel, before it is ever bonded to the nest. A flat face can be clamped while it cures; that is what a curved wall makes impossible, and it is the main reason the column is square.

Why square and not a cylinder

  1. Every sealed joint needs a flat surface. An O-ring or bulkhead cannot seat on a curve, and a riser welded to a curved wall cannot be clamped while it cures.
  2. Sourcing. Large-bore cast acrylic tube is a specialty, cut-to-order, sold-by-the-foot item. Flat ¼ in cast acrylic sheet is a commodity.
  3. The Ytong core. Turning a block of aerated concrete to fit a bore is real work. Cutting a standard block to fit a square box is two saw cuts.
  4. The camera. Curved acrylic distorts; flat faces do not.

The honest cost is four longitudinal seams where a tube has none. Flat-panel solvent welding is the most solved problem in the material — every acrylic aquarium is built this way and holds hundreds of pounds of water. This one only has to hold ants.

Key dimensions
Column section 8 × 8 in internal, 8½ in external, ¼ in wall
Nest 12 in tall
Bay 4½ in tall (two ¼ in plates + 4 in clear)
Outworld 8 in tall
Overall 26 in / 660 mm
Bay plates 10 × 10 in, ¾ in overhang on all four sides
Bay enclosure 5¼ in square external
Risers 3 × ¾ in OD × ⅛ in wall, centres 3¼ in from the axis
Riser collars 2 in OD, four per riser
Drawer opening 3¾ × 2¾ in; tray 3½ × 4½ in; portal stiles ½ in wide
Base 16 × 16 in, ballasted
Reservoir 131 mL

The section is 8 in rather than 6 because the bay has to hold a drawer wide enough for the controller board and leave three ½ in riser bores inside the outworld floor, clear of the walls. Below 8 in those two demands collide.

Cost and sourcing status

Links last checked: 2026-09-03. A ✔ price was read off the vendor's own page on that date. A ~ price is an estimate from typical US retail and has not been quoted — Amazon serves no price to an automated fetch, and Amazon prices move weekly anyway. Treat the total as a planning figure, not a quote.

Line Qty Price Basis
Adafruit SHT31-D breakout 2 $13.95 ea — $27.90 ✔ adafruit.com, in stock
Adafruit IR break beam, 3 mm 3 $2.95 ea — $8.85 ✔ adafruit.com, in stock
Tetramorium immigrans colony 1 $28.99 ✔ statesideants.com
Acrylic tube, ¾" OD × ⅛" wall 2 ft $1.10/ft — $2.20 + cutting ✔ canalplastic.com
Cast acrylic sheet, ¼", cut to size ~10 sq ft ~$80–120 ~ est. $8–12/sq ft cut-to-size
AAC block, 24 × 8 × 4 in 1 ~$20–60 ~ see the sourcing note below
Kamoer NKP peristaltic pump 2 ~$35 ea — $70 ~ est.
IR ONVIF / RTSP IP camera 1 ~$35 ~ est.
Weld-On 4 + Weld-On 16 1 ea ~$25 ~ est.
ESP32 DevKit 1 ~$12 ~ est.
DS18B20 probes, 5-pack 1 ~$13 ~ est.
Soil moisture sensor 1 ~$8 ~ est.
IRLZ44N MOSFETs, 5-pack 1 ~$8 ~ est.
WS2812B rings 3 ~$15 ~ est.
12 V DC heating cable, ~20 W 1 ~$18 ~ est.
12 V 3 A PSU + buck converter 1 ea ~$22 ~ est.
40 mm 5 V fans 2 ~$10 ~ est.
Float switch 1 ~$8 ~ est.
Drawer slides, 4" travel 1 pair ~$12 ~ est.
Fluon PTFE Plus, 10 mL 1 ~$15 ~ est.
Gasket sheet, toggle clamps, thumbscrews — ~$30 ~ est.
Ballast, base stock, moat tray — ~$30 ~ est.
Silicone, mesh, tubing, riser caps — ~$33 ~ est.
Perfboard, JST, glands, passives, wire — ~$35 ~ est.

Planning total: roughly $560–640, excluding tools. Two lines dominate it — the acrylic sheet and the pair of peristaltic pumps — and between them they are about a third of the build.

Sourcing the nest core

This is the one part that could actually stop the build, and it is the nest core.

The good news: one standard block is exactly enough. The commodity 4 in AAC block is 24 × 8 × 4 in (600 × 200 × 100 mm). Cut it in half and you get two 12 × 8 × 4 in pieces; trim each to 10.5 × 7.75 in and they are the two slabs this core is made of. The block's 4 in width is the slab thickness as sold, two slabs back to back fill the 8 in internal section exactly, and 7.75 in leaves a quarter inch of clearance across. One block, two cuts, almost no waste.

The bad news is buying one. Raw autoclaved aerated concrete is a commodity in Europe and genuinely hard to buy in small quantities in the United States — most US builders moved away from it, so the domestic manufacturers that exist (Aercon, Litecon) sell by the pallet, and a pallet runs into the hundreds of dollars for a part worth about $30.

What the ant-keeping market sells instead is finished Ytong nests (Esthetic Ants via American Ant Supply, Just Ants) — but those run about 108 × 63 × 28 mm, an order of magnitude too small for the 8 in core this column needs. They are not a substitute.

So, in order of preference:

  1. eBay. This is where ant keepers actually get AAC in the US, in single blocks. It cuts with a hand saw.
  2. Aercon direct. Keepers report emailing them and being sold material; worth an email before paying eBay shipping on a masonry block. A local supplier willing to break a pallet is the same idea.
  3. Pour the core instead — hydrostone, or a plaster and sand mix. It wicks, it is rigid, and it pours to any dimension, which removes the sourcing problem entirely. It is heavier and cannot be re-carved, and this design has not been checked against it, so it is a fallback rather than an equal option.

Settle this before cutting any acrylic. Every internal dimension in the build is set by the core, and the column is not worth building without one.

Not firebrick

K-23 insulating firebrick is the substitute the US ant-keeping forums reach for first, and on the face of it it is ideal: soft enough to carve with a plastic spoon, aerated, and it disperses water evenly. Do not use it here.

Keepers report that it produces an extremely fine dust, and that colonies held in firebrick nests for extended periods go sluggish and die without another explanation. This column is built around a colony that is meant to reach thousands of workers over one to two years in a nest that is never opened again — which is precisely the exposure firebrick is reported to fail at. The standard K-23 brick is also only 9 × 4.5 × 2.5 in, so it could not make this core in one piece anyway.

It is recorded here because it is the obvious wrong turn, and the reason it is wrong is slow enough that it would not be visible until the colony was established.

Two other gaps worth naming

  • Cast acrylic sheet is priced, not quoted. The ~9 sq ft is arithmetic off the panel schedule, and cut-to-size pricing depends on how many separate cuts the shop makes. Get a real quote from TAP, Acme or a local shop with the panel list in hand before ordering anything else.
  • Amazon links resolve, but ASINs rot. Every Amazon link in this file was confirmed on 2026-09-03 to still point at the right product. None of them are irreplaceable — they are all commodity parts, and the Notes column is the specification, not the link.

Cut list

Every acrylic part, ¼ in cast, ready to hand to a shop for a quote. Net area 8.1 sq ft; order about 10 sq ft to cover kerf and mistakes — for example one 24 × 48 in sheet plus a 12 × 24 in offcut.

Joint convention: butt joints, solvent-welded. In each four-wall box two opposite panels span the full external width and the other two fit between them, so the pair that fits between is ½ in narrower. Sizes below are finished sizes.

# Panel Qty Size (in) Notes
1 Nest base 1 8½ × 8½ The four nest walls land on it. Containment boundary.
2 Nest wall, wide 2 8½ × 11¾ One takes the capped expansion port, one the low intake
3 Nest wall, narrow 2 8 × 11¾ Fits between the wide pair
4 Nest ceiling plate 1 10 × 10 3 riser holes at 3¼ in radius, exhaust port, cable gland
5 Outworld floor plate 1 10 × 10 3 riser holes, 3 ring recesses, gasket rebate, cable gland
6 Bay enclosure wall, wide 2 5¼ × 4 Non-structural
7 Bay enclosure wall, rear 1 4¾ × 4 Non-structural; carries the terminal strip
8 Drawer-face panel 1 4¾ × 4 With the 3¾ × 2¾ in opening cut out
9 Portal stile 2 ½ × 4 Structural. Welded between the plates at the opening edges
10 Portal header 1 4¾ × ⅝ Structural. Across the top of the opening
11 Outworld wall, wide 2 8½ × 8
12 Outworld wall, narrow 2 8 × 8 Fits between the wide pair
13 Lid 1 9 × 9 Mesh aperture cut out; overhangs the shell by ¼ in
14 Drawer tray 1 3½ × 4½ Rides the rails
15 Drawer face plate 1 4⅝ × 2⅞ Gasketed, two captive thumbscrews
16 Riser collar 12 2 in dia Hole-sawed from offcut, bored to ¾ in

Items 4, 5, 9 and 10 are the load path and item 1 is the containment boundary; everything else is enclosure. Cut those five first and cut them accurately — the rest can be trimmed to fit, and these cannot.

The one clearance that matters

The bay enclosure is 5¼ in square outside, so 4¾ in inside. The drawer opening is 3¾ in wide, which leaves exactly ½ in of face either side — and that ½ in is where the two portal stiles stand. The tray is 3½ in wide and passes the opening with ⅛ in either side. Widen the opening and the stiles have nothing to stand on; widen the tray and it will not pass. Check these four numbers against each other before cutting anything.

Structure

Item Qty Source Notes
Cast acrylic sheet, ¼", clear ~10 sq ft Commodity — hardware store, TAP, Amazon Every panel is listed in the cut list above — 8.1 sq ft net. Cast, not extruded: it solvent-welds and machines far better.
Clear acrylic tube, ¾" OD × ⅛" wall 24" Canal Plastics — $1.10/ft ✔, sold in 12/24/36/72" lengths, cut to order Three load-bearing risers. An ⅛" wall on ¾" OD gives exactly the ½" bore this design wants — confirmed on their spec table. The only specialty part in the build.
Acrylic offcut for collars scrap from the sheet Twelve collars, 2" OD — four per riser
Weld-On 16 (thickened) + Weld-On 4 (thin) 1 ea Amazon / TAP 4 for panel seams, 16 for collar fillets
Ytong / autoclaved aerated concrete block, 24 × 8 × 4 in 1 eBay, or Aercon direct — read the sourcing note above The nest core. One standard block, cut in half and trimmed to two 10.5 × 7.75 × 4 in slabs set back to back, galleries carved into the outward face of each. Hardest part in the build to buy; settle it first.
Drawer rails, 4" travel ball-bearing 1 pair uxcell 4" full-extension, or Rockler mini slides 45 mm wide, 33 lb per pair — far more than a 1 lb tray needs; chosen for the full extension, not the load. Rockler mini slides are 3/8" thick if the bay gets tight.
Captive thumbscrews + threaded standoffs 2 + 2 Pull the drawer face plate home against its gasket. Nothing else holds the drawer in.
Panel-mount terminal strip 1 DigiKey panel-mount terminal blocks, or a panel-mount JST-XH board Rear of the bay. The rings and the nest fan land here; the drawer harness plugs into it. JST wire-to-wire is keyed and awkward to panel-mount, so a barrier terminal strip is the simpler answer.
Closed-cell gasket sheet 1 Drawer face plate, outworld shell
Toggle clamps or knurled thumbscrews 4–6 Compress the outworld gasket. Must be releasable by hand with the column in place.
Aquarium-safe silicone sealant 1 Gaskets and secondary sealing
Opaque sleeve stock (thin ply, ABS, or vinyl wrap) 1 Lifts off to view the nest
Ballast plate + base stock, 16" square 1 Footprint at least 0.6 × overall height, mass as low in it as it will go
Stainless mesh, under 0.5 mm aperture small Lid vent, nest ceiling exhaust port, nest wall intake port. Tetramorium pass anything larger.
Riser plug caps 3 Manual service closure — deliberately not powered
Shallow tray (moat) 1 The whole column stands in it. Last line of containment.
byFormica PTFE Plus Fluon 1 Band on the inner wall below the lid rim
Tetramorium immigrans colony 1 $28.99 ✔. Ordered last, after two weeks of empty running.

Hydration

Item Qty Notes
Small reservoir vessel, ~131 mL 1 Sized so its entire contents cannot harm the nest. This is the safety guarantee — see below.
Float switch, vertical, normally-open 1 Reads full. Wired so a broken wire reads "not full".
Kamoer NKP 12 V peristaltic pump 2 On the base, outside the column. One water, one sugar water — different fluids cannot share a pump or a line.
Water supply container 1 Any sealed jar, on the base. Refilled every few weeks.
Silicone airline tubing, 3/16" 1 Supply and feed lines only — no ant tube in this design

Controller and sensors

Item Qty Notes
ESP32 DevKit (ESP-WROOM-32) 1 Runs .NET nanoFramework. On the drawer.
Hilitchi DS18B20 waterproof probes, 5-pack 1 3 used (nest bottom, nest top, outworld), 2 spare
Adafruit SHT31-D breakout 2 $13.95 ea ✔ — 0x44 outworld, 0x45 nest, see below
DFRobot Gravity capacitive soil moisture sensor 1 In the Ytong core. Must be on ADC1.
Adafruit IR break beam, 3 mm LEDs 3 $2.95 ea ✔ — one pair per riser
IRLZ44N logic-level MOSFETs, 5-pack 1 All 5 used: heater, refill pump, feed pump, outworld fan, nest exhaust fan
WS2812B / NeoPixel rings, ~12 px 3 Bonded into recesses under the outworld floor, one concentric with each riser mouth. Chained on one data line over ESP32 RMT.

Power, climate, camera

Item Qty Notes
12 V DC silicone heating cable, ~20 W 1 OEM Heaters 12 V DC, 5 W/ft at 4 ft = 20 W, or a pre-assembled 12 V silicone heating wire. Wraps the outside of the nest section — no penetration at all.
Gdstime 40 mm 5 V fan 2 One in the lid, one bonded over the nest exhaust port. Both RH-gated, on different zones.
12 V 3 A PSU 1 Single supply for the whole column
Buck converter 12 V to 5 V (MP1584 / LM2596) 1 Feeds ESP32, fans, LEDs, IR emitters
IR-capable ONVIF / RTSP IP camera 1 Consumed directly by the dashboard. 850 nm is invisible to the ants and to us.
Rigid foam / cork sheet small Thermal break between nest ceiling and bay floor

Passives and small parts

Item Qty Notes
4.7 kOhm resistor 1 Mandatory 1-Wire pull-up. Without it no probe enumerates.
150 Ohm resistor 5 MOSFET gate resistors
10 kOhm resistor 5 Gate pulldowns — hold every output off through boot
SS34 / 1N5819 Schottky diode 4 Flyback across both pumps and both fans
Perfboard + screw terminals 1 Sized to the drawer tray
JST pigtails ~8 So every module disconnects for service
Bulkhead fittings / glands ~10 Bay plate penetrations — all flat
Hookup wire 22-24 AWG, heat-shrink, zip ties

Tools

Why the parts are what they are

Serviceability: three places to work, none of them the nest

The nest is never opened once the colony is in, so everything that might need attention has to be reachable from outside it. That splits into three:

The drawer carries what has firmware or a failure mode worth swapping: the ESP32 and the perfboard with all five MOSFET stages, terminal blocks and passives. It is a tray on rails behind a gasketed face plate on two captive thumbscrews. Pull it and nothing structural moves, nothing in the ant path is touched, and no weld is disturbed. The harness has enough service loop to reach the detent while still made up.

Bonded in the bay are the three LED rings in their recesses, the nest exhaust fan over its port, and the bulkhead connector strip. These are dumb and aligned to holes in the plates; re-aligning one is a worse job than replacing it in place.

On the base, outside the column, are both peristaltic pumps and the supply jar. Plumbing does not belong in a four-inch bay, and out there it is reachable without opening anything.

The outworld follows the same rule from the other side: its floor is welded to the risers and cannot move, so the four walls and lid lift off that floor as one unit on a clamped gasket. Cleaning is plug the risers, unclamp, lift, wash, reseat. No weld ever moves and the ring-windows stay put.

Passive hydration, and why the reservoir volume is the real safety feature

Borrowed from the way Tar Heel Ants build their nests: a reservoir wicks into the nest and is topped up every few weeks rather than sprayed on demand.

The pump fills only the reservoir, and the reservoir wicks into the Ytong core. Because its capacity is smaller than a dose that could harm the colony, no failure of the pump matters — worst case it overfills a vessel that is harmless when full. The guarantee lives in the geometry, where an electrical fault cannot reach it.

A second benefit falls out for free: refilling keys off the float switch, not the moisture probe, so a dead soil probe degrades the system to "passively hydrated, unmonitored" instead of stopping hydration altogether.

No gate

A powered gate between the colony and its food would be the largest single point of failure in the system: a servo that jams closed cuts the colony off from food and water, unattended, for as long as it takes someone to notice — and no firmware can distinguish a gate that is closed from one that is stuck. Three always-open risers give redundancy against one fouling with debris or a dead ant. Service closure is a manual plug cap, which cannot fail shut while nobody is watching.

Ytong nest core with carved chambers

One standard 24 x 8 x 4 in AAC block, halved and trimmed to two slabs set back to back, with galleries carved into the outward face of each — so the nest reads from two opposite walls, and moisture is uniform rather than the soil probe reading one arbitrary point of loose fill. Rigid galleries cannot subside. Ytong also wicks, which is what makes the passive reservoir work at all.

An opaque sleeve over the nest

Bare clear acrylic leaves the nest permanently lit by room light. Ants dig away from light, so that produces both chronic stress and a nest you cannot see into — they tunnel against whichever face is darkest. A removable opaque sleeve gives them darkness by default and gives you a full view on demand.

Nest ventilation without ever opening the nest

Three ½ in bores are not airflow. A Ytong core above 80% RH held at 27 °C is a mould risk the nest humidity sensor can see and nothing else could act on. A mesh-screened exhaust port through the nest ceiling pairs with a passive mesh intake low on the nest wall behind the sleeve, giving cross-flow bottom to top along the thermal gradient. The fan is bonded over the port on the bay side. Inside the nest there is only stainless mesh, which has nothing to fail.

A capped expansion port

Tetramorium immigrans was chosen precisely because it reaches 1,000–10,000 workers. A capped bulkhead port goes into the nest section during construction, while the box is empty, rather than being cut into a populated column later.

Two SHT31s, not one

The ADDR pin gives 0x44 or 0x45, so both share one I2C bus for one extra part. SHT31-A reads outworld air, which is what the lid fan can act on; SHT31-B reads nest airspace, where mould risk lives. Catching a moist-substrate / dry-air mismatch needs both.

Three WS2812B rings

One per riser mouth, in a recess under the outworld floor, shining up through a frosted annulus around each mouth. No ant contact, no moisture contact. Each riser owns an R/G/B channel whose brightness tracks that riser's traffic, closing a behavioural loop at the point where an ant picks a tube.

Ants are most sensitive to UV and blue-green and effectively blind to deep red, so the three channels are three very different stimulus strengths rather than three equivalent colours. The firmware rotates the riser-to-channel mapping at local midnight and logs it, so "they prefer green" can be separated from "they prefer the tube nearest the food dish". Without that control the experiment is uninterpretable.