Twenty years ago my neighbor, a retired surgeon, made me a PVC didgeridoo and did the wax buildup thing - I still mostly play that didgeridoo. Years later my wife bought me a traditional heavy didgeridoo from Australia, but it doesn’t play as well; still, when I played at a friend’s wedding I used the Australian one because it looks better :-)

I had excellent results using a large section of black bamboo, though I forget the exact taxonomy (lako?). I meticulously beat out the segment walls, then with a rasp fastened to a long stick, filed down the ridges. After sanding, I finished it with oil based stain, which necessitated it living outdoors for a while. In the end it proved a fine primitive instrument. I gifted it to someone and miss it. I can attest to the therapeutic effects of mastering the didge.

PVC works, but the acoustics do seem superior with actual plant material. Certainly the feel.

Update: I used beeswax for the gob hole.