A home-made oil-fired furnace, capable of melting iron - the results are good, I've seen both the rough castings and machined components from them.

The pattern is made from high density foam, the type available from builder's merchants. Produced substantially by hand using a Dremel, it is burnt away by the iron as it is poured. Although not required in this case, the technique allows for undercuts and does away with the requirement for any kid of draft angles, removing much of the complexity from components where the traditional alternative would be a multi-part pattern with cores.

Photographs used by kind permission of John Bayait.