It's my design :^)
For hobby foundry, if you stay on aluminium, electric is the best for health, security, quality and running cost.
this one was my first design with 3,2Kw power on 230V and can melt 5kg in less than 1H at about 40 cents cost here (11 cents €/kwh)
He was designed cheap but can melt alu at 800°C for a long time with no problem.

if you want to go to bronze (1150°C) propane will be way faster but still higher cost and less melted product quality.

I'm designing an improved version with 4kW and better insultation to catch easily bronze melting .
...i also have a rated 40Kw gasoil burner to try cast iron :^) but not the same race here.