This may be outdated, but take a large beach towel, sissors and drum key (or small metal thing that can be used as a small hammer-type thingy with you to camp... Cut in half on the short side creating 2 lengthy sections. (Example: One 4x2 towel becomes Two 4x1 Sections) Take one of the new sections, place one corner over the lug head closest to the harness crossbar on the drum 3... Take a drum key, gently tap the top of the lug area on the towel... You'll notice a worn area in the towel... Gently push worn area on the towel over the lug (it should be snug)... The towel should now be hanging on the drum by the one lug. Next, take the other end of the towel and wrap it around drum 3, around drum 1 into the gap between drum 1 and 2. Find a lug that is closest to the other corner of the towel around the area where drum 1 and 2 are connected together by the mounted spacer. Gently tap a hole to stretch over the towel. The cover should now be held in place. Go around the drums, stretching the towel in tapping over lugs as you go along. Don't stretch it so much that the original corner mount looses tension or the towel begins to tear. Towels naturally stretch, so work with the material, but don't over stretch it... Repeat the same from Drum 4 around drum 2... Lastly, you can take the sissors and cut the fabric to not cover the drums on the front side... If you do this correctly, you should need no pins, velcro or other fasteners to stay on the drums... AND it should only take 10 to 15 mins, depending how accurate you want to be...
Hope this helps, future cover makers...