/diy/ - Do It Yourself

I'm new at casting metal, I just made a furnace with some trash I had around, melted some beer cans by using charcoal and a blower I salvaged from a vaccuum cleaner. I used an instant coffee can as a crucible and pic related is my result.
I have some questions:

Is there such thing as "too powerful a blower"? The furnace lifted many sparks while I was melting, and it became very uncomfortable to handle.
May a stainless steel crucible improve my experience?
Which materials and shape should I make the lid of? I just used some steel sheet as a lid as a makeshift solution.

I've never melted aluminium before.