e2 tank engine ho scale motorized

This my first 3d model that I have ever built,because I had a lot of time in summer vacations so I decided to learn 3d designing. This is a E2 tank engine model(thomas the tank engine) sized in HO/OO scale/guage.It has semi details,You can motorize it with a 716 motor. It and has an power pickup system there is a hole between the last two wheels, over there you can insert a metal plate 2.25mm wide and bend it so that it touches the track then solder it to the motor wires.

I know this has a lot of non manifold edges,so i would want someone to fix it and make it 3d printable because i am not that good at fixing non-manifolds.

Please follow me because it took effort(20 days) to make.

thanks, bye