From the video and pics on FB they look to be made of steel with either a fine abrasive coating (diamond?) or perhaps more like files with the surface of the bit itself being etched or cut.
I've used pointed and narrow-diameter diamond-coated bits in my Dremel for years to do cleanup. The Hobby Element tools appear to be a nice refinement on that so I'm very interesting in getting a set. I look forward to hearing a few reviews first though.
Cheers,
Eric