On Saturday, December 7, 2019 at 6:12:08 PM UTC-5, soaringjac wrote:
Any recommendations on what to use to fill small holes in an aluminum panel?

Assuming 80 MM is a BIG hole...

How about another cool wiz-bang super-secret vario that just came on the market! At 57 MM for your convenience! Merry Christmas

On switch size hole... Do not plug! Part of the feng shui of a used or antique soaring plane...

(the other guys on this thread had some great ideas to plug) pouring epoxy in the hole that has tape on the back or Tig before you fill the hole. Countersinking a bit to spread the hole bigger may give you more surface. The biggest problem; the aluminum is thin to get a lot of surfaces to adhere to.... Bondo will fail in a short time because of the small amount of surface area...