I found myself having to go back and look these up in past designs, so here's a list of commonly used dimensions that seem to work w/ my printers.
M3
- M3 Nut = 2.825 (radius)
- M3 Hole = 3mm
- M3 Socket Head = 6mm
- M3 Support Nut Slot = 2.62 x 5.65 x 5.14mm past center of screw path
M5
Extrusion Rails
Draw an 8.5mm tall square the length of the part and extrude by 1.5mm Add a 1.5mm chaffer to top and bottom