Save those old credit cards
You probably get plastic cards in the mail all the time from AARP, AAA, AOPA, and gift cards. Don’t throw them away, they are great for mixing epoxy or even just putting a glob of glue down so you can use a spatula to place it carefully where it goes.
Old credit cards aren’t as good for mixing but they are stiffer so they are good for scraping. They are sturdy enough to get rid of grime and gunk but soft enough that they won’t scratch aluminum.