Real wood for feet that were built for branches. Aussie Bush Perches and the Birdnerd range, Beak Joy apple tree wood, java and liana from Ninos, natural vine, and multi perches with varying widths along the one branch.
Uneven thickness is the whole point. It moves the grip around and keeps feet in better shape than a smooth dowel ever will, and most of these can take a bit of chewing too.