Designed in Onshape: https://cad.onshape.com/documents/154f6352c0684ad1f6c7c213/w/fc14bd7f4f4cbd5dd5e331f6/e/c244bb19735c4b2673d084b6?renderMode=0&uiState=63bde45d48f6084327e491f7

Display: https://www.dfrobot.com/product-2107.html

ESP32 Board: https://www.dfrobot.com/product-2195.html

(See exploded view in “Full Assembly” tab of that doc for assembly order/instructions.)

Combined case for DFRobot 3.5" display and ESP32 firebeetle in an ultra-small, hand-held form-factor. Comes with a 3xAAA battery compartment with slide-off cover. 

Printed with 0.4mm nozzle, 0.25mm layer height, PLA. Supports needed for inner frame and shell case models.

The inner frame model was carefully designed and iterated on:

• Provides support for ESP32, battery compartment, without standing on any components or ribbons
• Includes channels and opening for routing some small leads between the ESP32 and AAA battery compartment
  • (it will be a tight fit to actually plug the connector into the ESP32)
• Includes an opening for GDI ribbon cable

Try not to over-tighten the screws, it's easy to strip these small screw holes since it's super-compact and there's not much supporting material.

Parts list:

• 3x AAA battery contacts, +/-
  • trim excess material on the sides of the contacts for them to fit
  • trim the spring on the negative contact, or it'll be too tight for batteries to fit
• M2 screws (see labeled pic for where each screw goes)
  • 2x 16mm
    • these screws come very close to the contacts for the bottom AAA battery. I suggest putting some electrical tape behind the contacts to make sure they're isolated (though probably unnecessary)
  • 2x 12mm
  • 1x 10mm
  • 1x 8mm
  • 5x 6mm (7x if using Sparkfun mini breadboard + 2x washers)
• One print of each attached STL

You can mix/match M2 screw length if you'd like, but these lengths and positions make sure they don't poke through the front of the case or into the back of the display.

Has some misc. features that I needed for my own use:

• Two screw holes for mounting a trimmed-down SparkFun mini-breadboard
• A small hole above the Vin pin for the display so it can be exposed and fully powered on/off by external circuitry

It could be made smaller by merging the AAA compartment and inner frame models, but this would make it much more annoying to print. Otherwise, attempts to make it thinner require removing even more supporting material, or switching to a different display altogether.

This isn't 100% finished, there are still some issues with the battery cover, but I'm not really working on this anymore and am releasing it as-is.