I did this piece just recently since I started thinking again about doing more than just prosthetics. This is latex, but it's not foam latex - pretty much the same as regular latex pullover masks. Painting them is a tricky process so I've been avoiding it.
I thought I'd start out with a couple pair of horns then I got this idea into my head and went for it instead. I'm pretty happy with how it turned out, it was a quick turnaround so it's not as perfect as it could be.
Overall it does give the look I was hoping for. It's pretty lightweight, attaches with a clear elastic thread which can be resized - and is dirt cheap to replace should it break and relatively easy to find.
I guess I'd call it a Demon Crown of sorts, makes for a nice addition to a prosthetic.
I'm looking at producing a limited number for sale starting in January - after a little more testing, I want to make sure the paint I'm using will hold up in the long run. Normally you'd use a toxic concoction of rubber cement and naptha to paint this with but I tried homemade Pax paints, seems to have held up well and once I get some proper glossy finishing paint it should hold up well.