I made the parts x motor m5 nut and x idler m5 nut. Its a very nice design, but unfortunately mine is a little under-sized. I don't know if it was my mistake, or the parts simply don't work with 8mm rods and LM8UU bearings..
It's generally recommended to use a drill on 3d printed holes anyway.
The parts are designed for 8 mm rods, and the hole size in SolidWorks is 8,2 mm. I agree that it is a tight tolerance for 3D printing. You can try to print the file a bit larger, or if you want a file with looser hole tolerance then let me know and I will make one.