I asked this same question, and got a PM from an exceptional 'nutter.
Pick up a 3/8" Treso ramrod ends ($7), then go to an agriculture supply (mine was a Coop. Get 1x electric fence pole 3/8" dia.. It's an exceptionally strong fiberglass. (aprox $2 ea).
Once you determine that length and cut, place one end in a drill, and mill the other end to the appropriate diameter with a file. Rinse / lather / repeat for the other side. Drill a hole for the cross lock pin and Epoxy the ends into place (being careful not to get any glue into the 10/32 threads.
For $9 you have an indestructible field rod far superior to most that are offered commercially.
Hakx.