If you removed the two center pieces and replaced them with a single piece with holes at opposite ends and on perpendicular sides then I guess you could use it as a "universal" connector.
Anyway, here it is in case you ever need it for something, whatever that might be.
Step 1: Tubing and Fasteners
You can buy 1" and 3/4" square tubing in 36" lengths at Home Depot for around 10 bucks a piece. Even if it were galvanized (You will also need some paint to keep it from rusting. Mine started rusting in the bag on the way home!) it would still be a ripoff.
OK, now that you are over Home Depot ripping you off you will also need a one inch length of 1/4"-20 threaded rod, four nuts and two small fender washers and two cut washers and two 1/4"-20 hex head bolts by 1-1/2" or 2" (whichever length has enough unthreaded area to prevent the nuts from getting closer than 1" to the hex head) and eight more small fender washers, two cut washers and four nuts. Out of revenge buy these at Lowes.
Step 2: Cut and Drill the 3/4" Tubing
Place a fender washer between each piece and insert a 1/4" approximate 1/2" threaded rod. On each end of the threaded rod inside the pieces of 3/4" square tuning add a fender washer, cut washer and nut.
Make whatever adjustments are necessary to the length of the threaded rod to allow the washers and nuts to be installed so that there is at least 1/4" space between the ends of the threaded rod and opposite inside wall of each piece of square tubing. (See picture.)
Step 3: Drill More Holes
Step 4: Cut and Drill the 1" Pieces
On the sides that are perpendicular to the holes cut along the edge and remove a strip of metal about 1-1/4" long. (See picture.)
Now drill your mounting holes or whatever.
Step 5: Add the Hex Head Bolts
Now mount a nut on the end of the bolt and screw it down to the bottom of the threads, add a cut washer and screw down the other nut.
Now repeat this prodecure using the other 1" piece.
Vah Wah Lah! Your three axis connector is now assembled.
...also please report any possible uses.