Ok.. I've studied on this for a while.
Everybody says (exaggeration) you can't cast 6061 it has to be wrought. If you try to cast it you get large crystals and poorly structured metal. One article I read about casting 6061 seemed to indicate that rapid cooling of sand type castings by blasting away the sand with water jets retarded crystal growth. As near as I can tell wrought means formed by working or under higher pressure. I'm sure somebody can provide a better definition in context. I think forming under pressure might also retard crystal growth.
Now one of the pretty well known enemies of aluminum casting is the formation of aluminum oxides during the melting process, and of course oxides that have already formed. Rapid melting with a forced air foundry as opposed to a naturally aspirated foundry seems to reduce this dramatically. Surface area of the starting stock is also a factor so even with a forced air furnace machined chips might not be a good candidate.
So why not use a steel die (permanent mold) with a cylinder shaped casting sprue, and then when full place it on a press with a piston to apply pressure. Then liquid cool it while still under pressure. If the process proves possible its all achievable in the conditions of a home shop. Well a home shop capable of making steel dies anyway. I would think pressure would have to be regulated so that cooling contraction does not destroy the part. The simplest shop press might not be upto the job as somebody would have to stand there surround by steam pumping the jack. LOL.
The biggest issue I see is figuring out how to cap the vents when the die is full so that you don't spray molten metal around the shop when you apply pressure.
I don't even know if I should post this... Ah what the heck.
Flame on. (pun intended)