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i wouldn't encourage using just craft foam, it will be rather floppy

Heh. I think about the only way to make a transparent sword is to cast it in resin, and I don't think anyone's crazy enough to do that. You have to make on out of wood, and make a mold out of that, and then pour the blade...too much work. Though it might be possible to make a transparent blade like you might make a wooden sword...if you had a giant sheet of half-clear plastic...

I noticed the theme of this thread and guessed it's probably most releted to my inquiry. I need to make the top portion of Elk's staff from .Hack and I am unsure what to make it from since texture is an issue.

The big crabclaw-like part looks to defy gravity...and since it's most often depicted in Ps2 game graphics I am unsure what texture is appropriate. I have a green shiny xmas decoration that could fit as the orb since it connects to the staff directly. (Unlike Tsukasa's which looks even harder to do)
Also, I am unsure as to how best to achieve the sculpting that the staff needs in order to look correct. If you have any advice on materials, technique, or both I would be glad to hear them ^^