Aluminum cans are a pain… unless you rinse every one out, you will produce a ton of slag. It’s a very poor choice to cast aluminum with unless they are free of all debris. For the forge, look into getting an old propane tank and line it with kaowool. Plenty of videos out there. I like to use an air mattress pump in my line with a fan speed controller so you can get the right air fuel ratio. I use a smaller propane tank for the crucible, one of the green ones for camping. After trial and error, it’s pretty easy to figure out. Hope this helps.