IMHO we can talk about fiberglass bows, their designs and performances. I have several old fiberglass recurves and compound bows to study them in comparison with wooden bows I make. But we are not expected to talk about how to make them here. As for the handle designs, almost any commercial flatbow will be acceptable, as most of them can be made in wood by hand. I personally think center-shot pistol grips are not quite "primitive" enough.