Here what we are doing-
Instead of PVC we used ABS (it is lighter). The Tube is 1.5in diameter. We put some caps at the end and did our best to find center. We have no lath but it look pretty good of the low RPM application. The hole was just the right size for some flange bearings to be pounded in. After that we we used the 1/2in aluminum rod that was in the KOP. Since the ABS is only supported at the ends we cut a fiberglass disc to fit in the inside diameter of the ABS. This provides enough support to keep the ABS for bowing in the direction of tension. Callers work great to keep the disc in place.
Stop! Don’t make the mistake we did, use polycord (here is a good
thread. To keep the polycord in place use a pipe size that will fit around the outside diameter of your pipe. Cut thin section of the pipe (1/2in) and glue them in with enough spacing for a polycord to fit between the two, now your set.
Here is a pic of your progress. We are not entirely done yet.
Hope it was helpful!
Good Luck!