As expected, the manufacturer is at
www.acculam.com (Accurate Plastics).
Some more distributors of the above:
k-mac-plastics.net
portplastics.com
acetal-rod-sheet.com (dead?)
phenolic-sheets-rods-tubes.com
sdplastics.com
calsakplastics.com
professionalplastics.com
modernplastics.com
plasticdistribution.net
(nikhsub1; you might want to check these out for Delrin (aka Acetal) tubes)