Coordinates: X from rear axle (forward +), Z from ground up, half-width from centerline. Changing tire Ø raises/lowers the whole rig — mounts and components move with the axles.

Drag components in the side view. Len > 0 draws the part to scale (e.g. full-length C1 body); mass acts at its center — split a part in two if its weight is biased to one end. Typical chassis rails: carbon 3mm ≈ 90–130 g/pair, alu 2mm ≈ 150–200 g/pair, brass skid 150–400 g.