Lowtides,
Try your local tackle shops. It is the same material that is used on umbrella rigs and diamond jigs using colored tubes. John B is on the money with Clemens Tackle.
If you look on the hand out I gave to everyone, 2nd line from the bottom of the page, Guide placement Aid.
After I finish spacing the guides, I mask off the area to be underwrapped. I slide back the rubber bands and remove the guides from the blank. Install the underwrap, remove the masking tape and apply finish epoxy, dry wicking to remove excess epoxy.
2days later, install the guides using the rubber bands to hold guides in place. Wrap up to the rubber bands. Then cut rubber bands with a razor or knife to remove them. Continue the wrap till finished.
Continue on with the project.
Capt Neil
Have Fun Fishing. Capt Neil
Custom Fishing Rods by Captain Neil