Is there only a certan amount of times you can ctretch and shrink metal before it cant be done anymore? If so does it weaken the metal.

Depending on the metal, you can work harden it. Ill use a paper clip for example.... unfold a paper clip... pretty easy right? now fold and unfold the same spot.... gets harder to do... that is because the metal is actually getting harder as you work it... eventually the paperclip will break because with strength... comes rigidity... and eventually brittle..

Over working the metal will cause it to become too work hardened and tear on you. If this happens, the panel is probably in bad shapre, which may require replacing the part.

well when you see a tool that is tempered it has gone through heating then rapid cooling to strengthen it but to much will eventually crack the metal