Step 1. Making the tray base
Place the two handle/support rails [A] on an even surface so that the front ends (axle end) are 75mm (3") apart (or a width that is slightly more than the thickness of the wheel), and the handle ends are 400mm (16") apart overall.
The tray base is made out of three 150mm x 25mm (1" x 6") boards [E] that are 400mm (16") long.
Place the three tray base boards [E] side-by-side on top of the two handle/support rails [A], forming a rectangle 400mm (16") x 450mm (18").
Refer to the plan drawing for position and fix them to the handle/support rails [A] with 50mm (2") stainless steel screws.
Step 2. Fixing the tray side panels
The ends of all the tray side and end panels have been cut 15 degrees off square.
Screw the end panels [B] to the side panels [C] with 50mm (2") stainless steel screws, but pre-drill the holes first through the end panels [B].
The side panels [C] sit on the tray base, but the end panels [B]
sit on the two handle/support rails [A], up against the tray base.
See the picture for reference.