Has anyone used steel for a form?
There are some big name brand bows as well as some custom bowyers that are made on steel forms they had rolled at a fab shop. It should last indefinately without warpage but cost prohibative for most of us on this site. If you settle on a design you really like go for it. I am still experimenting with design so I use wood and I doubt I will ever make enough bows of one design to wear out a good plywood form. A good wood form should last for many many bows. I think You would have to use heat strips because the form would weigh too much to lift and move around or put in a hot box.
About a year or so ago I saw where a couple of men made one out of aluminum. If you have the tools and materials I suppose it can be done.
if you had access to a ship yard that could cold roll and weld aluminum or steal that would be pretty snazzy!!....