All parts can be printed without need for support material The OSSM base is the most structurally important piece, recommend using 6 perimeters/shells and 30% infill. The threaded end mount should also have a good number of perimeters. Other parts are not so critical, and you can print with the settings you like on your printer.
You can either print the !Alternate Belt Clamp! 24mm Threaded End Mount.stl or OSSM Clamp Top and OSSM Clamp Bottom The threaded end mount now has the belt clamp integrated and secured by the jam nut.
The most recent tensioner SATC Improved Tensioner V3 allows you to get a far tighter grip on the belt but requires two 20mm M3 hex head screws, two M3 nuts and a 20mm M5 hex head bolt that is used for additional tensioning. Note this design contains two parts that are printed in place.