About this 3D model

Here is my DD (Direct Drive) extruder I designed for the E3D hot end. Mine is attached to an Ordbot but I included a body for 50mm (Mendel style) mount holes too. A Jhead hot end should work also but I have not tested that. The extruder was designed in Sketchup and I have included the .skp and .stl files. Parts needed: 1- The best hobbed extruder gear out there! 1.75mm gear http://www.ultibots.com/micro-extruder-drive-gear-1-75mm-filament/ or 3mm gear http://www.ultibots.com/micro-extruder-drive-gear-3mm-filament/ 4- 3 x 25mm bolts 2- 3 x 20mm bolts (for Ordbot mount) 1- 3 x 10mm bolt (for Ordbot mount) 1- 5 x 10mm bolt (for the bearing) 1- Bearing (625- 2RS or 625zz) 5x16x5 1- Spring 3/8" x 1-1/4" (Mine came from a Home Depot assortment box) 1- Nema 17 Stepper motor