This is an enclosure for a Heltec WiFi Kit 32 (v3) microcontroller (https://heltec.org/project/wifi-kit32-v3/), with holes for a power connector and aviation style connector to attach accessories, in the original case, individually addressable LED strips. The case could be a little more compact, however I've left some room for wiring and any additional circuitry.

The case lid holds the microcontroller, with a port for the USB connector, buttons, and a hole for the OLED.

To insert the microcontroller, push the USB connector into the hole, under the tab. Then use an M2 x 6mm self-tapping screw with a 2mm ID/5mm OD, 1mm thick nylon washer to secure the other end of the board. The board should sit in the recess on the post, and the washer should overlap the top of the board.

The body of the case has an 8mm hole at one end for a standard 2.5/5.5mm barrel connector, and a 16mm hole with locator sides for a multi pin aviation style connector.

Code for the project can be found at https://github.com/dpage/esp32-leds. I've also included the FreeCAD design in case anyone wants to make more complex changes.