All supplies purchased from home depot.
(4) 6″ wheels
(2) 1/2″x10″ Hex bolt
(4) 1/2″ washers
(2) lock washers
(2) Hex nut
(2)PVC pipe (pre-cut and threaded variety)

Cut Pipe insulation to fit PVC. Thread Hex bolt through PVC with washers at each end. Set tapered end of wheels facing inside of roller against PVC. This will minimize friction. Set lock washer to desired tension. Grinding down the threaded end will ensure the nut will stay on through use. Wrap foam with grip tape if desired.
Total cost of supplies $29.15.