Before the forward skin is riveted and only held in place by clecos or not in place at all, the canopy struts pushes the canopy forward at least 2/8 inches. Several builders uses bumpers to make sure the canopy stays in place both to avoid the canopy skin being damaged and also to have a stable canopy position when the rear window is aligned and installed
I had a look at a couple of solutions and came up with my own variation. I want it to be adjustable from the outside (when the canopy is raised) and I don't want the hardware dig into the canopy sub-structure.
I made Delrin bumpers that fit into the existing tooling holes and started making the bolt 'receptacles' from some beefy scrap angle (same as the F-705 angle stock).