Made a case for my Big Tree Tech TFT3.5 V3.0 display. Display is at a 45 degree angle from the vertical mounting plane. All fasteners are on the rear.
The display board mounts with #2 x 3/8" self tapping screws. M2 or M2.5 machine screws may work. If you need to drill out the display mounting holes, do not go any deeper than 8mm - this will leave 2mm of material from the bottom of the hole to the front of the case.
Case is designed to be rear mounted with M5 machine screws. It is advisable to tap the holes. I used a Greenlee drill/tap bit to drill the holes to the proper size and thread the holes. #10 machine screws should work, just drill and tap the holes first.
Am using this on two machines, my modified Folger FT-5 R2 printer, and on an MPCNC in an enclosure.For the FT-5, I mount the display to "BTT3.5v3.0_Case_Mount_r0.STL", securing the two parts together with M5x10mm machine screws. For my MPCNC case, I have a template (TFT3.5_Case_Drill.STL - thicker portion is the bottom) to guide in drilling the holes for the mounting screws and allow laying out the area inside that a hole can be cut into to pass the cables (do not need to cut out the whole area.)
There are two versions of the case. One has two holes on the bottom to allow access to two of the screws used to secure the display board - this one I used on my FT-5. Second version has holes for ventilation on the bottom - using this one on my MPCNC as the electronics compartment will have positive air cooling and this will be one way of allowing the cooling air to escape from the compartment.
The two cases shown in the pictures are printed in ABS with a 0.6mm nozzle at 0.3mm layer heights. Only need supports for the USB port hole and SD card hole.
If you are making your own mounting plate for the display case, the mounting holes are spaced 104mm horizontally and 54.42mm vertically.