I designed this case for NodeMCU boards which I use for my model railways. These cases are ideal to house a board for example running LittleYoda DCC Decoder software.
The case can be screwed together with M3 selftapping screws of 12-16 mm length. It has cutout slots for wires going to servos, LEDs or any other actuators on the sides, and another cutout for the USB. It has four flanges with 3mm sized holes, so you can screw or glue it under your model railway layout.
In my case, I put related wires in thermo shrinkage tubes, placed them in the slots, screwed the case shut, shrunk the tubes. After completing the tests, I used silicone glue to seal the slots, and some tape to cover the USB port.
Photo shows the draft print with my home 3D printer.