I'm with Roy on this one.

They like to charge 25 cents for a bolt, 75 cents for a washer, $1.50 for a
half dozen nuts, etc. I've got BOXES of exotic hardware for free from
disassembling things - and I use it constantly to build new stuff.

Built a small foundry almost entirely from old appliances, scrap, and other
wastes.

I think it's a good idea to try to use only automotive aluminum for making
castings, 356 pours like a dream, but some other alloys are rather nasty.
And, a good steam cleaning or powerwash prior to melting would definately
increase your yield and more sensible ion general.

You can get a ton of great electronic parts, motors, magnets from
microwaves, you name it.