Did Obi have a hood in TCW? I dont' recall off hand.. Anyway.. i pulled up this:
and it looks like four pieces per side for the upper body. So handguard, forearm, bicep and shoulder.
As far as fabricating goes, you really have to 1st decide if you're going to build off a model or just use your body. The latter tends to be much more cumbersome as you're constantly taking the part off and putting it back on, etc. Making a model gives you the freedom to keep the work on the table, in front of you for the entire process.
For the handguard, you could start with a lifecast of your hand using plaster bandages and then casting that with just about anything that would serve as a hand model. Plenty of how-to's on how to do that so I won't try and reinvent that wheel. Alternatively, the cheap route would be to just make a quick form of your hand with duct tape, fiberglass the inside of it, then pull the tape off before it sets up. That would give you a cheap but effective model to start working off of. Being as this is the smallest part, i would start here and work your way on up based on how you feel when it's complete.
For the forearm, the first thing i see is a prominent cone shape. Start looking and brainstorming about that shape... think large construction cones, decorations, posterboard rolled into a cone, etc. You have to be creative here.. you're going to form that shape out of something, cast it using whatever medium you choose for your prototyping and then do the same with the remaining shapes for that particular piece. Then you start sticking the pieces together. Keep your mind open here.. quite often, different materials will be better for certain things.. sweeping curves, straight lines, incuts, holes, protruding things, etc.
As this is a late response (sorry, i'm new too), have you made any progress on this yet? If so, post it up.. I'd love to see how it's coming along.
Cheers,
Daryl
