A tri-lam bow has 3 laminations, one for the back, one for the core and one for a belly. With the exception of a bamboo backing most other hard backings are boards as is the belly and the core.
If you choose a board that is appropriate for a backing it would also make a selfbow.
I think if you find an appropriate board or a good stave and take your time gingerly working out the tiller you also can build a successful bow.