Bolt bearing: 2x128 ZZ 8x12x3,5mm, Idler bearing: 1x 624ZZ, Nema 14 Stepper, as strong as possible (teste with 1,8kg Stepper), 2x M3x40 screw, 3xM3x20 screw, 3x M3x8 screw, 6x M3 nut, 1x M3 wormscrew max 4mm M3 washer 2x M4 Nylock nut, 2x spring for Idler (or cut one into half) brass d=2,4 D= 3mm, l ~ 20mm for the insert to the bolt, with this its also possible to print flex materials. If you use a normal 8mm hobbed bolt, you have to add the cone spacers, if you can make your own hobbed bold ensure that the teeth are on the right position.