2 Speed Gearbox (Without Engine)

A 2 speed transmission that can be attached to my 2 Cylinder Engine. If you wish to print this i have designed it to be assembled with 12 and 8 mm long m2 screws, 2 2 mm diameter metal rods at 53 mm in length and one at 4 mm in length, and 4 bearings with an inside diameter of 8 mm outside diameter of 22 mm and a width of 7 mm (standard skateboard bearing size). I plan on having this printed and will fix any parts that don't work correctly.