Fish tank question

[goddessofilm.livejournal.com]

Hello all. I searched the FAQ and found nothing of help, so I need to ask a question of sorts, referring to safe decorations for a fish tank.
I want to make a figurine of a camera or sync slate (I'm a filmmaker, so sue me) to put into my betta's tank with him. I'm not sure how to safely seal clay or Sculpey so that it's okay to put into the water with my fish. He's adorable and bored, so if anyone could offer suggestions on how I can bake and seal clay or something along those lines, I would love you forever... and Rosco P. Coltraine would be grateful for a nice new ornament in his tank. :)