OpenPuck – Snap-fit case for Pro Micro nRF52840 / nice!nano with soldered headers (parametric)

A two-part, screwless snap-fit case for a Pro Micro nRF52840 development board (nice!nano v2 compatible, SuperMini-style clones) with all header pins soldered on: both long rows and the 3 extra pins (P1.01 / P1.02 / P1.07) at the end of the board.

Most cases for these boards assume a bare board. This one is built around the soldered headers. The header plastic rests on a raised floor, the long pins drop into slots, and the USB-C port stays reachable.

Made for OpenPuck (https://github.com/safijari/openpuck): open-source firmware that turns this board into a replacement for the Steam Controller 2's "puck", the wireless USB receiver the controller connects to. The Pro Micro nRF52840 is the default hardware for it, because its radio supports all the wireless the puck needs. The case fits any Pro Micro nRF52840 with headers, whatever firmware it runs. It is not part of the OpenPuck project and not affiliated with Valve.

Tested with a "Pro Micro NRF52840 Development Board compatible with nice!nano V2.0". It has 13 pins per long row, because the header also goes through the B-/B+ holes. Its USB-C socket sits raised in the PCB cut-out instead of centred in it. The board drops in, the cable plugs in fully, and the lid clicks on tight without rattling.

FEATURES

Two parts that click together: the lid's skirt slides over a rim on the base and catches on a bump on each side. The catch is preloaded, so the lid is pulled down tight and doesn't rattle. To open it, pry at the notch at the end opposite the USB port.
Fits all soldered pins: the slots end right after the first and last pin, so the board can't slide when you plug in or pull out a cable.
Fits both 3-pin layouts: nice!nano v2 and SuperMini clones place the 3 extra pins about 2 mm apart. The default base has slots for both.
Reset access: these boards have no reset button. You reset by bridging RST and GND, and double-tap for the bootloader. Choose one of three bases:
base.stl: side window, so you can bridge the two pins with tweezers
base_rst_bottom.stl: slot in the floor, for a bent paper clip
base_rst_none.stl: fully closed
Engraved lid: "Open / Puck" plus a simple logo, sized so it stays readable with a 0.4 mm nozzle. The text, the logo and its size are all settings.
Outside size: 38.75 x 22.88 x 16.8 mm.

MEASURE YOUR BOARD FIRST

Clone boards differ more than you'd expect. Mine had two surprises: the header also goes through the battery holes, and the USB-C socket sits raised in its PCB cut-out instead of centred like on the official nice!nano. The STLs fit my board. If yours differs, check these with calipers and enter them at the top of the .scad file (my values in brackets):

PCB thickness (1.6)
header plastic height (2.5)
long pin length (6.0)
tallest solder joint above the board (2.0)
USB-C top above the PCB underside (4.0)
board length (32.9)
pins per row (13)

If you're unsure about your board, print the base first and check that the pins drop in before printing the lid.

PRINTING

Orientation: base upright, lid upside down (roof on the plate). The STLs are already oriented. No supports needed.

Walls: Arachne (variable-width) walls, 3-4 wall loops.
Lid first layer: the engraving is printed on the plate. Use elephant-foot compensation of about 0.1 mm and a first-layer line width of about 0.42. Wide first-layer lines fill the letters. A smooth plate gives crisper letters than textured PEI.
0.4 mm nozzle, 0.2 mm layers, 15% infill.
Material: PLA+ works well (that's what the tested case is made of). PETG flexes a bit more if you open the case often.

CUSTOMISING (OPENSCAD)

nrf52840_case.scad is fully parametric. Open it in OpenSCAD and use Window > Customizer. Useful settings:

rst_access: side / bottom / none
variant: both / nicenano / supermini
row_pins: 12 or 13 pins per long row
plug_w / plug_h: the USB opening; set it to your cable's plug body + 0.4 mm
snap_preload: lower it if the lid is too hard to close, raise it if the lid rattles
pin_slot: raise it to 1.3 if the pins drag
label / logo: the engraving; logo = "none" for text only, or "svg" for your own one-colour SVG
The GitHub repo includes a research report with all board dimensions, pin coordinates and sources.

TRANSPARENCY

I designed this with help from Claude (Anthropic's AI assistant) in Claude Code. I took the measurements with calipers and checked every step against test prints. Claude researched the board dimensions and wrote and refined the OpenSCAD model from them.

Source & full documentation: https://github.com/gira0/3d-prints/tree/main/nrf52840-case