Print the two side panels. I went with 40 % infill and they turned out

very sturdy.

Supports may be needed, depending on your printers bridging quality.

Cut to length six rods or tubes of 20 mm diameter.

Through 4 of the six rods, drill parallel holes of 3.5 mm diameter,

offset 4.5 mm from each end.

Place hex nuts into the slots in the side panels.

Place the 4 rods with holes in the outer slots in the side panel and

secure with the M3 bolts.

Place the remaing two tubes i the center slots.

Fix the second panel to the other side of the rods in the same way.