I think the current handles are molded and cannot be reused. Hobie used to use a hollow PVC handle though that was re-cordable. You can make one with 1/2" schedule 80 (for gray) or schedule 40 (for white).
--Trim your PVC to length (about 4")
--Round off the edges with a file or sandpaper
--Drill a hole in the middle just large enough for your new lines to pass through
--Pull the lines through and tie the ends together in with a simple knot
--Stuff the knot back in the tube
Below left is a pic of our first Hobie tandem with original handle -- worked great! On right is a similar "T" handle that was easily made to haul a ballast tube.

Or you can buy a new molded handle for about $10.
