What about doing a Ontario old hickory 14" butcher knife project ?
They may not be what the majority of people imagine when they think if a Bowie, but large butcher knives just like the old hickory were extremely popular on the frontier and far more common that what most think of.
You two could have fun together doing something like a sinew wrap on the handle and make a simple rustic / primitive style leather or hide sheath for it.
This is just a thought that nobody be else has recommended, and things like this are always fun and more special.
The knives are in stock now, the materials aren't hard to get at Tandy leather ...ect, and it's a project that could be completed in a couple of afternoons depending on what you do.