Building the Mount
For the most part I followed Gary Seronik's plans carefully. Since I intended to install the mount on an equatorial wedge, I modified the size and shape of the bottom plate to match the circular outline of the wedge as shown below. Also since my supply of scrap plywood did not include any 1/2-inch plywood as called for in the plans, I used some nice 3/4-inch plywood. This change could make the mount a bit heavy for installation on a photo tripod. So in that case it might be best to stick with the plan's use of 1/2-inch plywood.
Gary's plan uses what looks like a pair of door hinges. I chose to use a single piano hinge, which allows the hinge to be the full width of the upper plate. I also relocated the ball-head camera mount from the center of the upper plate to the top edge, as shown in the above photo. This was necessary to avoid the problem of my articulating camera monitor not being accessible when the camera was pointed up.