The wing itself should tell you I'd imagine. If it's built, just measure the diameter of the sleeve in the panels and you can pick up an appropriate diameter CF tube. By inserting a straight pushrod, into the sleeve, you'll also get the required length in each panel. Add the fuse center portion and you can cut the tube to length. There are several sources for CF tubes none of which come to mind now... (Take it back, maybe Budd engineering but there are much larger and varied sources.)

David