But I did want it to be easy to assemble and disassemble so I could use just the original four foot hose or the combination of the two for twelve feet. Here is what I came up with.
I figured that the wire used in an all wire coat hanger was just the right material. I found one in my spare bedroom closet, cut off the hook, and straightened out the remainder with my bench vise and a small ball-peen hammer. I cut off about 15 inches of the wire and bent it into a square "U" with a 2.5" middle segment. Then I used a piece of one inch PVC pipe in the bench vise as a form to bend the two legs into 270 degree arcs.
About the first half inch of those arcs from the sharp, 90 degree bends was straightened in the vise jaws and the ends were cut to leave about 3/8" more than 180 degree arcs. About 1/4" at those ends was also straightened out. The ends were filed (sand paper would also work) to remove the burrs left by cutting. The ends are nice, half ball shapes that will not cut me or harm the vacuum hose.
This clip easily snaps on the ends of the two hoses and holds them together very well. It adds almost nothing to the diameter of the hose.
With this simple clip I can join or separate the two hoses in just a few seconds. Here you can see the nice, long, twelve foot hose on my shop vacuum.
It works like a charm. The combined hose acts like a single, longer hose. I used it on my track saw to cut the board that the vacuum and hose is resting on. I can leave the vacuum on the work bench and easily reach the work in the middle of the floor. And in just a few seconds the hoses can be disconnected and I am back to the original, four foot hose which is handy for many other situations. It is the best of both worlds. Not bad for $21.99, an old coat hanger, and a couple of hours of my time, including shopping for the hose.