Summary

slotcar chassis for GoPro Hero Session action cam
made for ball bearings and 2mm axles
guide needed

carrera go motor or any other FF030 motor
28tooth spur gear m0.5
8 tooth pinion m0.5 (one with 1,5mm for motor, one with 2mm for intermediate axle)
i´m using ball bearing for all axles 5x2x2.5mm (2mm axle, 5mm outside diameter)

front wheels max. diameter 11mm (camera holder can drag with bigger wheels)
rear wheels min. 16mm