These jigs should help drilling holes in aluminium profiles that line up with taped ends of other profiles.
Designed for 6mm groove profiles.
The 66, 70 and 86mm dimensions were especially made for the Muldex 3D printer design from John Mulac: https://github.com/3dprintingworld/MULDEX
The drilling holes are designed for a 4mm drill bit.
The hexagon hole is only there to put a screw to hold the jig in place, I just find that hexagons print cleaner than round holes when printed vertically.
The author marked this model as their own original creation.