After the resin with micro was cured it was time to sand the filler away.
I received the 1 inch sanding pads, but they were quite aggressive.
Instead I followed the same procedure as another Sling 2 builder and purchased some nail files. First pass with #80 grid, then #150 grid and a final pass with Skotch Brite:
It took about 2 hours to sand all 4 mm rivets on the upper side of both wings.