In some occasions, you will need to rivet blindly. For example when rivetting the leading edge assembly to the main spar.
First tip : A good idea in this case is to use some vision aid in form of a webcam.
You can find a detailed description in the wing section on the article 'rivetting the leading edge to the spar'.
Second tip : To control the size of the rivet shop head in unreachable or invisible places, a good tip is to use your skin. Your what ??? Yes, your skin.
Push your index finger hard on the shop head for about 5 seconds. Take your hand out and look at your finger. It shows the inprint of the rivet head in your finger skin.
For the beginners, you can compare this diameter with the diameter on the rivet gauge. For experienced builders, you can ballpark the size of the head to determine it's quality.
Good Luck !
