Cut two 10" long pieces of 3/4" PVC conduit. File the burrs off the ends. Mark each piece for three holes in a row, one in the middle and one 1-1/2" from each end.
Drill three 11/64" holes in each piece at the marked locations using a vise and drill press if possible, but a handheld drill will work. Drill all the way through the pipe since the other side needs large holes to let the screws through into the pipe.
Turn the pieces over and enlarge the holes on this side to 3/8" diameter. I used a Unibit step drill to save time.
The last photo shows what the finished holes should look like.