90 Degree Joining Plate for 2020 extrusion and M3 screws

There are a few 90 degree joining plates out there, with holes sized for M5 screws. I wanted to use these 3D printed T-nuts (https://www.thingiverse.com/thing:3050607) that use M3 screws, but the M5-sized holes on the joining plate were almost as wide as the head of an M3 screw.

I used the .step file here (https://grabcad.com/library/v-slot-90-degree-joining-plate-1) and shrunk the hole sizes to be 3.1mm, which is just about perfect for an M3 screw to slide smoothly through.

In the slicer, if you cut the plate so it is 2mm thick, it will be perfect for 8mm length screws, though at a loss of strength. Otherwise 10mm length screws should fit the default 4mm thickness.