Thanks for the compliments, Robert!
I used a Crossman air pistol from Wal-Mart for the base. The only true 'reference' photo I had was from the BF magazine, that had a decent shot of the barrel from the front. By that time, I had already put on eight ribs, which I thought was correct. I had to trash the barrel, sand it down again, and glue TWELVE instead.
The only thing I'd like to replace is the 'D' piece that connects the stock to the rifle. I used two sheets of Sintra and JB Welded them together. It's sturdy enough for display, but not quite strong enough for everyday usage. I have to be real careful when I troop. It's hard to explain to a kid, "No, you can't hold the gun, because it might break in the middle."
Someone makes those 'D' connectors in aluminum, I think. But I'm not sure what mods I'd have to make to the rifle to support a different piece.