While working on the wingtips the wings are in a perfect position to fill the top rivet heads.
I mixed some epoxy resin with micro-balloons:
With a syringe it’s easy to fill the rivet heads and after filling I removed possible air pockets with a lighter:
Time to cure:
After a couple of hours the resins kicks, it’s easy to remove the excess material with knife and using a washer (1.2 mm thick and inside hole of 8 mm for the 4 mm rivets) as a guide:
I ordered some 1 inch sanding pads to final smoothen the rivet head.