Okay I'm done with my first one. Here are the major problems that I will have to fix on my next one.
The cover that goes over the Heavy Bolters is too short, probably due to the thickness of my cardstock.
Both sides of the Chassis is too short, again probably due to my cardstock.
The small tabs that go on the door, I'm going to redesign them to go through the door, glued on from the back. This will increase their stability. On the half built Rhino I made they all broke off.
I messed the tracks up big time. They seem longer than they need to be.
I have parts left over due to them not being on the instructions.