Here’s a look at the case I designed and 3D printed for my OnStep Controller. The primary electronics are an ESP32-based board such as the Wemos D1 R32. This is paired with Roman Hujer’s OnStep Shield and some TMC2130 SPI steppers.
Box was made to accomodate a 50mm 12v fan I had available, but could easily be sized to fit a 40mm fan if desired. Honeycomb vents on the top of the box.
Fully parametric Fusion 360 file can be found here, as well as STL files for the top and bottom. Don’t mind my messy fusion model, I’m no expert, but I’m sharing the parametric model so you can modify as you want.