Precious Metal Clays (PMC) are strange, wonderful things. In the 1990s, Masaki Morikawa found a way to mix metal dust with an artificial, burnable clay like material. You mold and shape the PMC into the desired shape, then fire it a kiln just like normal clay. For some smaller pieces, you can use a blow torch, rather than a kiln. What you are left with is pure metal - if a bit less dense than the normal stuff (it has holes where the clay used to be). But it is almost 100% silver/bronze/gold/copper/steel once fired.
I used silver because gold is very expensive. But even silver is expensive. It's not just the clay (which obviously costs more than regular silver). You also need a small kiln, and I would strongly recommend classes unless you are just working with the base metals (bronze/copper/steel). Otherwise you will waste a lot of silver/gold learning simple things.
It is very easy to work with and requires no muscle. But if you want to make something fantastic, you may need more skill. I was capable of making a ring and earrings.
Typically you use it to make jewelry, though you could use it to make anything out it. You could in fact make a bronze key, fix a broken zipper pull, a can opener, etc. It's pretty sturdy.
Like most jewelry making classes, the far majority of students are female. The woman that taught me focused on an older crowd, though that might be different at different places.
I took classes here: