Originally Posted by sandman

I've measured the tube with my digital caliper.

The O.D. is 0.770 and the I.D. is 0.700.

That matches with a T-20+ from Totally Tubular (erockets now)

http://www.erockets.biz/Totally-Tubular.html

The inside tube will be a BT-20.

It may be hard to glue the BT-20 in without it grabbing on you.

The other cheaper alternative is a standard BT-20 with the tube coupler inside and building up the O.D. of the BT-20 just at the ends where it's glued into it's mating parts.

You could do that with just strips of paper glued on the ends.