My Nephew

He's such a cool little dude and my brother, his dad, just hates fishing and the outdoors, so, I just gotta work out, like you said, the 'details' on how to help 'em become an independent little fisherman dude.
Like you saw your friend walking across a pitching deck, I watched Aidan climb down a little hill the oher day. I used to have to carry his butt down it, but now, he just charged it . It was a great moment.

Sounds like you're on the right track.  Contouring can be very customized by using duct tape for the shaping; it's tough, fairly waterproof and you can replace it whenever you want as needed.  You might need a strap to hold the piece onto his forearm under load.  I'm thinking if his arm is bent roughly 90 degrees, the strap would hold to the lower part of his upper arm just above the elbow, around the lower part of the triceps.  Another strap would harness lightly around his shoulder to keep the first strap from falling down.  Motion would be unimpeded and the piece can't fall off.  Another thought is to space small foam strips inside the piece to make lands and grooves like in a rifle barrel for a little ventilation to keep the sweating down a bit.

Keep us informed.  I think the harness offer is stellar and will provide a good base and maybe all he needs.  If not, I am willing to put in the time to help make whatever is needed. 

Oh boy; I wasn't thinking about it being that high up his arm. The two pieces are from just below his elbow to the wrist. I think I messed it up; the more I thought about what you wrote the more it made sense. I'm trying to arrange a trip with him this weekend. Unless my desing is killing him, he won't say a beep, so ya got some things I should be looking for, in terms of performance?
When I get a good picture of his arm and his waist size, I'll post and, for sure, I'll post the updates. I'll take some fishing pics too. His smile when he's fishing, is all the evidence needed to prove the potential addiction fishing poses to the lucky few.

Before you get too crazy about manufacturing,
Think simple - if I understand you correctly his arm works fine (shoulder and elbow) and he only has issues with his hand. If this is correct take a look at a Fighting strap http://www.hellotrade.com/blue-water-of-california/fighting-strap.html this simple devise will allow him to set the hook by pushing down on the butt of the rod with a simple movement of his elbow. This would also allow him to install and remove on his own which will give him more independence. 
For more info give Tim Sellars a call. Tim Manages our store in Manteca and lost his hand at a young age. He will be more than happy to give you any advise in what this young man could do to help him get fishing.

Fisherman's Warehouse Manteca - (209)239-2248

See Ya Soon,
Eric / Yakhopper

No, we're on the same track.  I was just thinking of something to lock it in when on a big fish in case it started to slip.  The unit itself would be what you already have more or less.  The FW guy will be a big help; he's already been through this.  I'll be in Monterey taking MBK's basic class on Sunday; I'll pass you twice.  I'm not sure of my schedule, or yours for that matter, but I'll let you know and maybe we can hook up.  Regardless of how you end up addressing it, it'll get done and the boy will fish independently. 

The boy seems unlikely to indicate something not right; you just have to watch him closely without being obvious (side note: love your shades).  My sister has made a career out of helping little children just like him; hobbies and activities are a wonder.  She combines her loves of children and horses, gets the little ones on her horses and teaches them horsemanship.  The progression from internalized, shy and non-verbal to outgoing, confident little chatterboxes who chew gum and kick ass brings good things to all.  Frankly I'd like to see him in the running for AOTY next year so I can listen to the competing "men" argue "assisted fishing."   

Too cool.  More power to you and your nephew!  And everyone who helps out.

I finally got some pics of little man's hand. My device would have probably ripped his arm out of his shoulder, so i'm still working on somethin.

Our first big bass; check out the smile on this dudes face. His right hand shows the "natural" position it rests in.