Here are a open wagon for the TKTrain system based on kBricks construction system (https://www.thingiverse.com/thing:3574234). Some elements you needed from kBricks and any you can download here.

In the following table the sources for the pieces

train_base_4 (here) train_wall_corner_solid (here) train_wall_solid (here) plate_2hole_rounded_inline_centered (kBricks) peg (kBricks) train_wheel (here) train_buffer_plate (here) train_plate_4_side (here) train_coupler (here) connector_short (kBricks) connector_long (kBricks)

The instruction for built the wagon is in work.

Another wagons, engines, tracks and any more are in work and coming soon.