It printed up nicely. I just need to make another extruder head and finish up my homemade optocoupler. For us US types, 4-40 hardware will work for the M3, but it is worth looking for the M5 that Vik suggests. I just wish that I could find a longer nut for the interface between the M5 grub nut (with the hex hole) and the M5 bolt. I can only get one thickness of M5 nut around here, apparently.
It was worth printing out just to see all the clever 3D features, like the holes to hold the opto board, which are printed at 45 degrees.