I remixed this design to mount my 3.5 touchscreen and a Raspberry Pi 3B+. The mounting holes for the RPI are oversize so I could use some M3 screws I had here. You will either need to open up the holes in your PI or make the ones smaller in the model before you print it.
Touchscreen link: https://www.amazon.com/gp/product/B07N38B86S/ref=ppx_yo_dt_b_asin_title_o09_s00?ie=UTF8&psc=1
Update
3mf file added.
The author remixed this model.