We have one gung-ho iai-do student in our dojo who made his own tsuba a couple of months ago. It's actually a fairly simple process called lost-wax casting, & is used frequently to create custom jewelry. He teaches art at a high school & has access to their kiln.
He used Monel metal, by the way, which is both dense & strong. The tsuba has stood up well so far. His comment was that removing & reinstalling his tsuka was by far the hardest part, as 11 different "thingies" fell out, ranging from a toothpick to three shims. He also had to add one seppa, which he also cast.
Ken Goldstein
--------------------------------
Judo Kodansha/MJER Iaido Kodansha/Jodo Oku-iri
Fencing Master/NRA Instructor
"A positive attitude may not solve all your problems, but it'll annoy enough people to be worth the effort."