model manual transmission

My idea was to better understand how a manual transmission works by actually building a model of one. My model has 5 gears and a large cutout to better understand the inner workings of a transmission.  

Additional requirements for assembly: four 3x10mm screws and 4 bearings size 6004, 20 x 42 x 12. Free STL files on thingiverse with this link: https://www.thingiverse.com/thing:4821342

Assembly: 

1. glue the 5 input gears, e.g “1 gear ip” = first gear input, to the input shaft. Be careful not to mix up the input and output shafts and later gears. The input shaft has 5 areas to which the gears are supposed to be glued to. These areas are marked by little dents on the outside of the shaft.
2.  slide the output gears ("1 gear op" = first output gear) onto the output shaft, make sure that the order of the gears and their rough position is correct. Use the pictures, or your previous knowledge on manual transmissions, to ensure that is the case.
3. pair each output gear with a “synchro ring (print 5 times)”. The output gear and the synchro ring should sit directly next to each other, with only a small gap visible.
4. line up and glue the 3 hubs and "shift sleeves" to the output shaft. Some of the output gears will not be able to be removed after this bit, so compare with the pictures to make sure there are no mistakes! Again, the output shaft has three marked areas to indicate where the hubs should be.
5. insert the 4 printed bearings into the corresponding holes on the “input side housing" and “output side housing”
6. fit both shafts to the bearings and the inout/output side housing
7. fit all three "shift forks" to the shift sleeves. The fit should be loose, so that the output shaft and the gears can still rotate independantly of each other.
8. tricky part: insert the middle housing between both side housings, while guiding all three shift forks through the slots in the top of the middle housing.
9. use the screws to connect the middle housing to the side housings,
10. install all three shift arms. The longest one is responsible for the first gear, the straight once lets you change between second and third gear and the thirs shift arm, which is also short but has a bend, lets you shift between fourth and fifth gear.

you now have a functional manual transmission. Moving the shift arms up and down allows you to switch between different gear ratios. Both shafts feature a keyway so that you can attach this other other things, for example an inline 4 cylinder engine, a differential or many other things.