Saving your skin
The aft edge of the fuel tank skin is really hard on your arm when bucking the forward most rivets on the first rib. I found this soft rubber hose (1/4 inch thick) in my garage and decided to make an edge cover out of it. I cut a slit in it and put on the edge of the tank skin.
Here's a shot of the foam rubber hose on the tank skin
This was a lot better, a nice cush for resting my arm while riveting.
Tried it out on the wing ribs
Yep, that'll work. I seen pictures on other builders web sites where their arms were all red from reaching in through the lightning holes to buck rivets and install stuff. This soft foam rubber hose is the kind of hose that goes over air conditioning pipes, not the pre-split hose for outside water pipes. The pre-split water pipe insulation is too stiff for this type of application.