This x-carriage works with a standard wade's or makergear extruder and 8mm smooth rods at the standard spacing.I was getting sick of having to tear apart my whole machine or reprint entire axes every time I wanted to upgrade or replace a part, so I've started creating simple modular replacements for the x-axis. In this case, the carriage has brackets to attach a belt clamp, fan mount, pen holder, etc etc.Now if you change your x-ends and the belt doesn't line up, just print a new clamp instead of a whole new carriage.Print the carriage rotated onto its side. Insert 4 igus bushings into the ends of the rod holes and slide onto x-rods.Print one or two belt clamps and attach to one side of carriage using m3 screws/nuts (there are nut traps underneath the brackets).Feed a cable tie through the small recangular holes on the belt clamp and tighten it around the belt.My belt offset may not match yours, so modify the belt clamp module in the scad file as you need and re-print.The mounting brackets have m3 holes spaced 15mm apart if you want to create a fan mount or any other accessory.