This is a replacement for the eMaker / RepRapPro Huxley part. The original is laser cut MDF and can be prone to snapping. This printable version also features a shim that accounts for the space between the mount and the drive body- so it fits a bit nicer.This part doesn't really carry much load but for rigidity it's good to go for ~25% fill.Assembly is the same as the original part: The holder should be secured to the frame providing a bracket to mount the extruder drive. Place an M3x20 bolt with a washer through the bolt hole. Attach the drive and then secure with another washer and a nylock M3 nut. Use a cable tie in the bottom hole of the extruder driver, to fasten it to the machine frame.