Space out the Y-axes during montage When you build the Prusa I3 3D printer, you have to space the Y-axes exacly 16cm apart and parrallel. During assembly this tool helps you space-out the correct distance for the Y-axes threaded rods. Align the Y-axes belt It also helps to align the Y-axes motor and idler because there is a center mark on this spacer tool. Only short usefullness This makes the assembly a bit easier, however you will need it only for a couple of minutes during assembly.The design is very simplistic, I have saved some fillament by placing some extra holes. No special slicing tips or settings required.