Designed for Solidoodle 2, a more compact spool holder less than 10cm deep. Fits colorfabb standard spools, should fit any spool with a depth no greater than 7cm and centre hole of at least 4.5cm diameter. Might fit other Solidoodle models, can't check as I only own SD 2. For Bowden: Will work with future bowden extruder project. For Direct: Recommended Filament Guide (Coming Soon) INSTRUCTIONS tab for how-to.1) Print all parts with at least 3 perimeters, recommended 30% infill. 2) Sand the inside lip of the tube to press together tight. 3) Apply Super glue, wait to dry. 4) Screw into holes for original filament holder, only 2 are strictly necessary especially for smaller spools. 5) ??? 6) Profit.