We here in our community want to build our bwiti inside and out. This means having the Mogongo and a Ngombi at our disposal to learn to work with via the sacrament. For now we are working on building our own Mogongo to start with. I asked my brother who plays Mogongo for instructions and this was his response.
"If you can get the materials. For the arc, you need a supple new growth hardwood, 2 or 3 seasons old. Have to cut it fresh, shape it. The string is rattan material. the m'basso you can make from a bamboo, I think." ~ Bovenga
Hope this helps!
Basse!