I made a set of these based on the OP's concept - but modified by necessity as I couldn't find the copper pipe, so......
I used regular 1/2" copper couplings that have the small indentation at the mid-point that you shove the copper pipes up to to center the joint.
I used the double ended 1/4" x 2" furniture screws to join the two sections of dowel together by drilling pilot holes in the ends of the dowels and epoxied the screws into the dowel used for the lower half.
I slightly beveled the two ends of the dowel joints to fit just past the copper coupler centering ring to make sure the dowel faces would have full contact with each other.
Slipped the copper fitting over the end of the bottom dowel and "pinned" it to the bottom dowel with a centering punch. This way the copper fitting stays attached to the lower section of dowel when I take them apart. My hope has been the copper coupler would provide enough support to keep the screws from breaking out of the dowels - so far so good.
I adjusted the height of the assembled sticks by cutting from the bottoms of the bottom dowel sections and I used 1/2" rubber feet for canes instead of the copper caps.
Finish was simply rubbed on a couple of coats of mahogany tinted furniture wax with some fine steel-wool.
With this set up I have a full size (standing) sticks and I can unscrew the bottom sections, pull off the rubber feet and put them on the bottom of the top sections and use the same set of sticks for sitting/shooting from a ground blind.
