Another technique is mokume gane but some people suggest that you should have a plain inner core to prevent electrolytic action from salts in your skin
This one is another engraved / carved ring and I think artcarved have similar to this one, but others such as BEL also have good examples and I think White Flash has their own engraver if you wanted to design your own.
If he likes more 'techy' rings then I spotted one with Steel and Carbon Fibre a while ago but didn't save it. Sorry!
I think I am the only wife who has a husband with a collection of wedding rings. The two-tone with white gold etching is his original band (I have the match) which is 18 years old and still looks pretty good. The plain gold band was purchased shortly after the wedding so he wouldn't bang up the *real* ring. He wears that when he is doing yard work, construction around the house, or working on the cars. The diamond band was purchased at about the 7th anniversary. It looks nice when the husband is all shined up. The titanium band was purchased this year for an 18th anniversary gift. Mr. DiamondLil does not wear any other rings, but changes his wedding rings depending on his attire. Sort of like me and my jewelry.
This is my husband's ring from titaniumstyle.com. His first ring was white gold and looked so bad after a month that he decided to ditch it for titanium which he loves.