About this 3D model
When assembling this most excellent model, I found that the front wheel wasn't manifold. Every time Cura sliced it, it would fill in the top as a solid, obscuring the hub. This is a repaired, manifold version of that front wheel. All of the other parts can be downloaded from the original upload. You can see my make of the complete model here - https://www.thingiverse.com/make:369549