I use this PETG printed spacer along with a 5/16-inch threaded knob to lock my truck box down to my truck bed rails. (You may need to drill through your plastic rail covers, but my metal rail already had the threaded hole beneath the plastic covers.) It forces the box to a centered position and keeps everything held down very tightly, especially if you add a nylon wingnut or print your own PETG threaded block (not included in this design).
Printer Brand: Prusa
Printer: I3 MK3S
Rafts: No
Supports: No
Resolution: 0.2 mm
Infill: 15%
Filament: Prusament PETG Orange
The author marked this model as their own original creation. Imported from Thingiverse.