Happy Bubbles Enclosure
The Happy Bubbles Bluetooth Presence Detector shipped as a bare board. One per room, each publishing what it heard to MQTT, and Home Assistant finally knew which room a key fob was in — but a naked PCB sitting on a bookshelf looks like a naked PCB sitting on a bookshelf. This is the case that fixed it: a flat oval puck in two parts, no screws, a window for the status LED and a notch at one end for the USB cable.
Happy Bubbles the company is gone and the board has not been buyable for years. The case is still worth printing, because the thing that replaced it — an ESP32 running ESPHome as a Bluetooth proxy — is also a bare board on a shelf, and there is room for it in here. Every measurement you need to check that is below.
The measurements
There is one STL and it holds both halves, already laid out side by side on the plate. Everything here is measured off that model.
| Assembled | 71 × 64 mm, 12.9 mm tall |
| Base (the taller half) | 71.2 × 64.4 × 10.3 mm |
| Lid | 71.3 × 64.4 × 7.2 mm |
| Interior | 65.6 × 57.6 mm, 10.9 mm deep |
| Wall | 2.8 mm, stepping to a 1.06 mm lip above the seam |
| Floor and lid plate | ~1.05 mm |
| Port notch | 12.4 mm wide × 7.2 mm tall, lower edge 3.2 mm above the interior floor |
| LED window | 3.0 × 5.2 mm rectangle through the lid |
Two things follow from that table and they are most of what you need to know about this print.
The board only goes in one way. The port notch is at one end of the oval, split across the seam so half of it is in each part, and the LED window is offset toward that same end — the orientation is decided for you.
And there is nothing inside to hold the board. No posts, no standoffs, no screw bosses anywhere in either half. The lid pressing down is the retention, which is fine for a board that weighs nothing and never moves, and is why you want a pad of foam under it.
Parts
Some links below are Amazon affiliate links. As an Amazon Associate I earn from qualifying purchases — at no extra cost to you. It helps keep these guides free. Outside the US, they should send you to your own Amazon store; if one doesn't, searching the part number there will find it.
- PLA+ filament, 1.75 mm — a 4 kg pack of black. One spool is dozens of these
- Matte PLA, 1.75 mm — the better call for a case that lives in a room at eye level. Matte hides layer lines, and the logo debossed into the lid reads properly instead of disappearing into the gloss
The board that goes inside:
- A Happy Bubbles Bluetooth Presence Detector, if you still have one. It was sold direct by Happy Bubbles, never through Amazon, and the company shut down — there is no honest link to give you
- ESP32 dev board, 38-pin DevKit — a 2-pack, and what to build today. This is a substitute, not the original board. It is roughly 52 × 26 mm so it drops inside easily, but it does not share the Happy Bubbles layout: its LED will not land under the window and its USB socket sits lower than the port notch. Read the ESP32 section below before you print a lid
Power and mounting:
- Right-angle micro-USB cable, 1 ft — a 3-pack. The right-angle head keeps the lead flat against the shelf instead of standing the puck off it. The plug moulding has to clear 12.4 × 7.2 mm, so measure yours
- Dual-port 2.4 A USB wall charger — a 3-pack of cubes, two nodes per cube
- 16 ft flat micro-USB extension — for the node that wants to be above a doorway, where the socket isn’t
- Industrial hook-and-loop, 2 in × 15 ft — the right way to hang this on a wall, because you will want it back down again to reflash it
- 3M VHB tape, 1/2 in × 15 ft — if it is never coming down again
Worth having on the bench for this one in particular:
- Deburring tool and assorted wet/dry sandpaper — the lip fit is tight enough that you will use both
- Digital caliper — for checking a board’s USB socket against a 3.2 mm number before you commit to a print
Print settings
Both halves are already sitting flat on the plate in the orientation they want — base opening-up, lid face-down. Print it as exported and there is not a single overhang in either part.
| Setting | Value |
|---|---|
| Layer height | 0.2 mm |
| Perimeters | 3 |
| Infill | 20% |
| Supports | None |
| Material | PLA or PLA+ |
| Orientation | As exported — do not rotate |
PLA is right here. This is an indoor part that never gets warm, and PLA holds the 1.06 mm lip more accurately than PETG will. Save the PETG for the sensor that lives in the garage.
The lid’s outer face is the one against the bed, and the logo is debossed into it 0.23 mm — one layer. Print it on a smooth sheet and it comes out crisp. Print it on a textured one and the deboss competes with the texture and loses.
The lip is a press fit with almost nothing in hand. The base’s lip measures 67.7 mm across, the lid’s cavity 67.9 mm — 0.08 mm of clearance per side, which is less than one printer’s worth of variation. Expect to run the deburring tool round the top edge of the lip and the inside edge of the lid rim, and to knock the elephant’s foot off the base’s first layer, before the two go together. That is normal for this model, not a sign you printed it wrong. Take material off the lip, never off the inside of the lid, or you lose the seam.
Assembly
-
Deburr both mating edges before you try anything else — the outside top edge of the base’s lip, and the inside edge of the lid’s rim. One pass with the deburring tool is usually all it takes.
-
Dry-fit the empty halves. They should go together with firm thumb pressure and stay together. If you have to press hard enough to flex the walls, sand the lip: 400 grit, a few strokes, check again. Do this now rather than with a board inside.
-
Check your board against the port notch. The opening starts 3.2 mm above the interior floor and is 12.4 × 7.2 mm. Sit the board on the floor of the base and look at where its USB socket lands. If the socket sits low, pack the board up on foam tape until the plug goes in straight — a plug levering against the edge of a printed notch is how a micro-USB socket gets torn off a PCB.
-
Line the LED up with the window, note which way round that puts the board, and stick it down. Foam tape underneath does two jobs: it sets the height, and it stops the board rattling, since nothing else in there is holding it.
-
Power it up and confirm it is on your network before you close it, because opening this case again is a fingernails-and-a-guitar-pick job.
-
Press the lid on with both hands, thumbs at the two ends of the oval, straight down. Rocking it on one end first is what splits a 1.06 mm lip.
Putting an ESP32 in it
The honest version: this case was drawn around a board that no longer exists, and the inside is a plain 65.6 × 57.6 × 10.9 mm cavity with no features in it at all. That makes it a generous, indifferent home for almost any small ESP node — a DevKit uses about half the floor — and it makes the port notch the only thing you have to get right.
Flash the ESP32 with ESPHome’s
bluetooth_proxy, on top of
esp32_ble_tracker. That
is the direct descendant of what the Happy Bubbles board did: it hands Home
Assistant a Bluetooth radio in that room, and tracks iBeacons by UUID on top of
it. One per area, same as before. It must be an ESP32 and not an ESP8266 — the
ESP8266 has no Bluetooth radio at all.
Two things do not carry over. The LED window is a 3 × 5 mm hole in a fixed place, and a DevKit’s power LED will not be under it — either accept a case with a hole in it, or drop a 3 mm light pipe in and run it to wherever the board’s LED actually is. And the port notch sits 3.2 mm up, so a DevKit lying flat on the floor of the case puts its socket below the opening and needs shimming.
Print the base on its own first and try your board and your cable in it before you print six lids. Ten minutes of print time answers the only question that matters about a case you did not draw.
What it is listening for
A presence detector is half a system. The other half is a small radio that talks constantly, never needs charging, and is attached to whatever you want located.
- Tile (Gen 2) Bluetooth tracker — the era-correct one, and what was on the keyring when these detectors first went up. Current Tiles rotate their Bluetooth address for privacy, which is exactly the behaviour that breaks address-based room tracking, so treat this as the historical answer
- BlueCharm iBeacon — a plain iBeacon with a fixed UUID is the reliable modern answer, and it is what the BLE Hub config is written around. These come from BlueCharm rather than a generic seller, so a search is the honest link
- Xiaomi Mi Band — a beacon you were going to wear anyway. This is a Band 4; the newer ones are the same idea
Troubleshooting
The lid will not go on. Almost always elephant’s foot on the base’s first layer rather than the lip itself — the widest part of the base is the bit that touched the bed. Chamfer that edge with a knife and try again before you sand anything.
The lid goes on and will not come off. There is no fingernail relief anywhere in this model. Slide a guitar pick or a spudger into the seam at one of the narrow ends and lever gently. If you expect to open it often, put a tape tab under the board so you can lift the board out without fighting the case.
Range is worse in the case than out of it. The plastic costs you very little. Where you put the puck costs you a lot — flat against the back of a steel appliance, inside a cabinet or behind a mirror is a node with half its Bluetooth range gone. Height helps more than anything else; above a door beats ankle height in the same room every time.
A beacon reads as present from two rooms away. Not a case problem, and not fixable by moving the node. RSSI reads like a distance and is not one. Use it to answer which node hears this loudest, never how far away is it.