So here's an SCAD implementation. It's done as a module so it can easily be tacked onto other objects. I put them on Greg's X carriage in about 10 minutes (I'll post this later after I print a test one).This is a fresh implementation made by just printing one of the original objects, measuring it and bashing it out in SCAD. Enjoy.print, use.Modify SCAD file if you need different dimensions.