I see mad 3d domain rush right now but imo most of the domains ppl register is shit...
at the beginning only top ones will count like for example 3dporn.com, 3dsex.com 3dtits.com...
Fortunately, I managed to register really top ones like e.g. 3d+"niche".com
btw if you are interested in what I've got and prices you can shoot me an email.