I think that the opportunities to do that are long gone, at least in the .com TLD department, there isn't that much left to register that makes sense, it is extremely difficult to hand register a .com that makes any sense. There are a few .info and .biz but I am not sure how valuable those will be in the future with hundreds of new TLDs coming into the arena.
I hand registered a few 3D domains a couple of years ago and so far it has been a total failure, I have not sold any of them and I don't think they will take off in the next 5 years at the very least and after that maybe a new technology will come along rendering those domain useless. If you are going to keep domains for years that's lots of money that quickly adds up.