I bought 10 pieces of 20' thin wall 1/2" PVC pipe. I can't remember exactly how I cut them. I think I cut 2 pieces up at 34" which gave me 14 pieces and I already had a section or two from another project. You can get 5 - 48" pieces out of a 20' piece so it took 9-20' sections to get the 48" pieces for 15 coffee cans.
So you would need 11- 20' sections and a extra piece at 34" to come out right for 15 coffee cans.