We use some 1/2 inch plastic PVC pipe, with connectors. They come in 6 or 8 foot lengths, put together several to span a longer area, using duct tape to hold them together when in use for easy teardown and storage. Flexible enough to go around a 90 degree bend in a 12 inch cable tray, but stiff enough to guide through most obstacles. You can easily cover 20 feet or more with 3 lengths of pipe. Rather inexpensive, as well.