In my case, I will use 3mm plywood, to the bottom plate.
dimensions 530mm L x 84mm B
The walls are made of cardboard, which I glue thin wooden slats on. As picture shows.
Buffer plank, reinforce the underside of the bottom, with a piece of wood about 6 x6mm. To obtain a larger surface to glue on. as shown on the photograph. And a piece of wood to the boogie. as shown on a picture. for better movement of Boogie. (just one piece, here I have tried myself to find a solution)
The small hinges to the gates, shall be mounted on the gable, can be glued with acetone.
The windows have a groove where you can insert a piece of clear film. in my case clear transparencies, or packaging of a clear plastic.
The shaft for the brake handle, I used a slim skewer.
The roof I do with paper that I glue on to sawn pieces of wood, similar to the gable in shape.