did you consider a small fixed blade like a Swedish Mora, or ESEE Izula....
Along these lines, a Grohmann
You-Make-It knife kit might be fun. I believe most of their
outdoor knives are available in kit form; the
#2 seems well suited to the younger guys.
It may also worthwile to check out their
clearance page to see if there's anything that strikes your fancy there (me and my son have the X107SD Outdoor Knife).