Step 1: What You Need
---A 1/2" type T fitting (a tee like you might get with plumbing pvc except it opens to allow pulling wires through)
---four 4m metric screws (the length will depend on the thickness of the next item needed)
---Something to mount the piping on (I had a used piece of 1/2" plywood that I didn't even have to cut!).
Tools: Screw drivers, a drill, a pencil, measuring tapes, something to cut your PVC, and a straight edge.
Step 2: Getting Started With the Mount
Once you've done this you can measure out the dimensions of the mount on the back of your monitor. Mine happens to be the VESA 100mm x 100mm standard. There is also a smaller 75mm x 75mm standard for smaller monitors. Check your manual to see what the dimensions are so that you can measure it properly.
Mark the spots for the holes with x's and drill with a bit slightly larger than your screws.
To mount the T fitting to the board, drill holes through the back of the fitting and screw it to the board.
Step 3: Fitting and Cutting Supports
Cut your PVC tubing a little longer than what you need so you can fine tune it based on the size of your monitors and the size of the speakers you'll be mounting.
Step 4: Drilling the Supports
Step 5: Hiding Wires
Drill a hole in the bottom of the T fitting and you'll be able to pass all of the speaker wires through the bottom and hide them behind the base of your monitor.
Step 6: Finished Product and Thoughts
The PVC at this short of length is pretty rigid so it doesn't sag with my speakers. If your speakers weigh more you can use PVC or metal strapping to screw it to your mounting board.
I didn't glue the PVC to the T fitting. The tight fit of the pipe into the fitting is enough to support my speakers. If not, then try gluing it or use a pipe support like I mentioned above.
You can use this as a springboard for doing all kinds of things. Make it out of aluminum, steel, steampunk it out with copper and brass, whatever you want. You could also use this in conjunction with an articulating arm mount. Go crazy.