Casting aluminium is easy. My first castings were made about 5 years ago when I lived on the Falkland Islands. Supplies were tricky to obtain so I had to use what I could get. For my furnace I managed to find some old fire bricks from Rayburn cookers, I crushed them up and mixed then with fire cement that came ready mixed in small, very expensive pots. I can't remember the exact mix but it worked, the lid of my furnace broke up a little bit but it did the job. For casting sand I had to use sand from the beach mixed with cat litter. For fuel I used peat, sometimes difficult to light but free. I made many successful castings.
When I returned to UK 3 years ago I was excited at what I thought would be the easy availability of materials. But, everything is so expensive here, plus the area that I live is not industrial so I had to travel long distances to obtain materials. Eventually I had built a furnace using posh firebricks, then came the problem of fuel. First I tried charcoal from B & Q,. it was out of season so they were selling it off cheap. But what sort of charcoal was this? To suit "modern" life they had made it easy lighting. You cannot believe the smoke it produced for the first 15 minutes! It blanketed the road where I live. To this day I am amazed that I did not get complaints from neighbours. So, I went over to propane, at first I was concerned about the cost. If you have seen my build log on my milling machine you will see that I have made quite a few castings. So far I have used one cylinder of gas that cost £27. That doesn't seem too bad to me. If you can make your own charcoal as Steve (vtsteam) does, or have free peat, then go that way but I think that propane is simply the best.
As far as casting brass or iron goes, it scares the s--t out of me. Stick to aluminium (or if you are from the colonies, aluminium).
