Hma Radio PTT Switch Enclosure for M12 Push Button, Snap-Fit Magnetic Base

Overview

A compact desktop housing for the common 16 mm, M12x1 thread momentary push button (the red-cap style). The base snaps on without screws, a hidden magnet holds it to steel surfaces, and the cable enters at an upward angle to keep strain off the solder joints. The housing is about as small as it can be while still fitting the switch and leaving room to tighten the mounting nut with a socket from inside. Overall size is about 39 x 39 x 34 mm.

On the Air

This is a shack desk PTT for any rig with a PTT jack. It sits next to the paddle or keyboard, so you can key up without reaching for the hand mic and keep your other hand free for logging. The flared base keeps it from tipping when you press it, and with the optional magnet it stays put on a steel desk, rack, or monitor stand. Check your rig's PTT jack pinout before wiring the plug.

It works equally well as a push-to-talk button for Discord, OBS, or streaming, or anywhere else you need a momentary switch on the desk.

Print Settings

- Nozzle: 0.4 mm

- Material: PETG. The snap arms flex every time the base is removed, and PETG handles that much better than PLA.

- Layer height: 0.2 mm

- Walls: 3 to 4 perimeters. This matters for the snap arms.

- Infill: 20 to 25%

- Supports: none

- Part cooling fan: 30 to 50% for better layer bonding

- Orientation: housing upside down (top face on the bed) for a clean button surface; base flat with the snap arms pointing up. The files are already oriented this way.

Hardware and Assembly

- 1x 16 mm momentary push button, M12x1 thread, 14 mm hex nut - https://a.co/d/0c0HcPWF

- 1x cable, up to 4mm diameter (for example a 3.5 mm TRS lead or 2-core cable) - https://a.co/d/04eEv9E3

- 1x 10 x 4mm neodymium disc magnet (optional) - https://a.co/d/088R9mhC

- 4x 6mm adhesive rubber bumpers (optional) - https://a.co/d/0gwRro6B

- CA glue for the magnet (optional)

- 14 mm socket for tightening the nut (See Print Files)

1. Clean any PETG strings off the snap bumps and grooves.

2. Press the magnet into the pocket under the base, with a drop of CA glue if you like.

3. Feed the cable in through the angled hole and solder it to the switch's two terminals.

4. Push the switch up through the top panel, thread the 14 mm nut on from inside, and tighten it with the socket.

5. Line up the base with the cable notch at the back and press it on until both sides click.

6. Add the rubber feet.

7. To open, put a coin or flat screwdriver in the front pry slot and twist.

Design Notes

The model is fully parametric in OpenSCAD with Customizer support. You can adjust switch hole, nut, and body sizes; cable diameter and entry angle; magnet size, fit, and pocket position; snap fit snap_depth, snap_preload, crush_rib_interference); wall thickness, base flare, and corner radius; and foot size.

When you change the snap settings, the console prints an estimate of how far the snap arms bend. Keep it under about 2% for PETG.

Fit tips:

- Base too hard to snap on: lower snap_depth to about 0.55.

- Base rattles: raise crush_rib_interference to 0.25.

- Magnet loose: lower magnet_fit_clearance to 0.1.

Printed and fit-tested in PETG with the default settings.

Makes, remixes, and fit reports with other switches or rigs are welcome.