This thing is a support for a RepRapDiscount Full Graphic Smart Controller. It is designed to be mounted on the left side of a Creality Ender 3.
The support is attached to the printer using the original screws. The display is attached to the support using four M3*10 screws. I do not have the original screws that attach the screen to its support; these might work. Please let me know if you try!
I upgraded my Ender 3 with an MKS Gen L main board and silent stepper drivers from Trinamic. I wanted to use an SD card, so I had to replace the original display by one that has an SD card slot. The RepRapDiscount Full Graphic Smart Controller does not fit inside the original display support. I, therefore, designed a support and placed it on the left side because it makes cables routing easier.
I printed mine with PETG, it probably works also with PLA. I used a 0.4mm extruder and printed with 3 walls and 20% infill. No support is needed.
My Youtube channel: https://www.youtube.com/channel/UCbzywNRA6k0vM5E_KwfFXcQ
My website: https://jleclerc.net/