Very nice. I can understand a project that needs doing...
My old tumbler was built from an old film reader projector. The bearing surfaces for the support rods were just holes drilled through the wood endplates.
Low RPM's seemed to be no problems with wear.
My can was a old style steel coffee can with small wood paddles similar to your shown in the internal photo.
One of my many mottos is: "save money, no matter what the cost!"