This is the plan for a set of monitor arms that I recently built for my new desk. This desk is based on the plywood top from my original desk, but for I purchased a height adjustable frame for this desk.
I've been using fully adjust monitor arms for a number of years, but they are heavy, and I realized that I never actually adjust them. I decided replace them with something fixed, and this was the solution that I came up with.
The total cost for these monitor arms was about $40, including the glue and all of the screws needed to mount them.
Step 1: Parts
After much planning, and several hours spent wandering around a home improvement store, I decided to use 2" black ABS pipe and fittings to build the stands. You could just as easily build it from PVC, and then paint or dye the PVC parts.
The base of the mount is made of two parts. A flange, and an adapter. The flange is actually for a 3" or 4 " pipe (there were no 2" flanges available), and the adapter goes from 3" to 2".
I also bought some slip connectors so that I could cover the hole from the top, and create a stronger mount. This isn't entirely necessary, and could be left out, especially for smaller monitors.
Step 2: Planning
For my desk, I wanted to have the flanges mounted to the bottom of the desk, and only the pipe come through to the top.
This adds additional complexity to the design, since the holes must be drilled in exactly the right location, or the monitors won't be located correctly.
This also meant that I had to contend with the frame of the desk, and make adjustments to the location to accommodate the cross member.
This aspect of the design can be changed quite easily so that the flange can be mounted on the top of the desk (as explained in the next step).
The pictures below are of the completed mounts.
Step 3: Assembly
Since I decided to mount the flange to the bottom of the desk, I inserted the adapter into the flange backwards. If you wanted to mount the flange on the desktop, you would insert the flange backwards from the way it's done in the pictures.
Since this is backward from the way that the flange is designed to mount, it's fairly stiff, and takes quite a bit of work to get it inserted. Since it was so snug, I decided not to disassemble and glue the joint, but if it was mounted the other direction, I would probably glue it.
I then cut and drilled short pieces of PVC pipe for test fitting the mount.
Step 4: Monitor Adapters.
Since I already owned a set of monitor arms, I used the 100mm adapter from those arms as a size and drilling guide. Most monitors have a standard VESA mounting pattern, so you'll have to check your monitors to determine the location of the holes.
I ripped a piece of plywood at 5" wide, and then cut 3 squares just under 5".
Then I temporarily attached the old mount with screws to use as a guide.
Once I had drilled the 4 mounting holes, I then drilled the center hole, and hammered a long bolt through the hole.
Step 5: Drilling the Desktop, and Test Fitting.
I had an extra piece of plywood left from the desktop, so I test drilled and fitted with that piece.
I then made adjustments to the measurements, and drilled the actual desktop.
The two extra holes in the desktop are for the cable grommets.
Step 6: Mounting the Flanges
Once the desktop was stained, varnished, and mounted to the frame, I glued up, and mounted the flanges to the desktop.
I glued a 2.5" piece of pipe into the flange, and then screwed the flange to the bottom of the desk. Then glued the straight connector to the top of the pipe, sandwiching the desk between the two pieces. This design is permanent, and required that the holes be very exact in order for the monitors to line up.
Once mounted, I reattached the PVC test pipes to the monitors to get a final measurement for the pipe sections that would hold the monitors.
Step 7: Finish
With the final measurements done, and the ABS pipe cut and drilled. I mounted, and glued the upright pipes in place.
I got the center monitor done first, carefully measuring to get it level, and parallel to the desk. After allowing it to dry, I did each side, making minor adjustments to both the height, and angle of the pipe during the gluing process.
As an added bonus, the pipes are large enough to run the cables through them, so there's no exposed monitor cables on the desktop.
I'm very happy with this design; It's very rigid, and feels like it will hold up for a long time. The frame under the desk is height adjustable, and there is no shaking or movement from the monitors while raising and lowering the desk.