I would agree with Arthur, don't waste your time with the hollow core. I think i did all the polycord for
610's 06 bot in like an hour by melting the ends with a one of those small table top heaters (melting the material on a piece of AL placed on top of the heater as to not ruin the heater) and then stuck them together and trimmed the excess with a exacto-knife. Polycord make belting systems really easy to put together, not tight enough just cut a bit off and reattach.