Custom-Casting Ring & Setting?

[RWX]

Hey guys, anyone here have experience custom-casting your own ring and setting? A friend of mine had previously CAD-designed and cast his own ring and setting (with some help, obviously), and I am seriously considering giving it a shot as well for my proposal/engagement ring. The stone itself is going to be a beautiful 3.05 VS1/F 3EX round brilliant diamond, so I'm a bit nervous but still excited at the prospect of doing the ring myself.

Anyone have any particular suggestions or experiences? The rock's a bit big, so I'm thinking I should make the band slightly thicker as well so it matches a bit. I have a small bar of gold which my grandpa purchased ages ago for me, and was planning to alloy it with some nickel to produce a nice white gold alloy, then use that to actually cast the ring itself. Already beginning to play with 3D CAD software...

 

[foxinsox]

No experience with actually making the ring but if you have the tools, I assume you can do a good job. I would ask a few things, how are your finishing skills? Can you be sure the diamond will be safe in the setting? What sort of setting does your intended want? How thick are you thinking about making the band? Thick bands aren’t very common these days.
Is nickel a good metal to alloy given how many people are allergic to nickel? Do you know if your intended is ok with nickel?