Paul,
Here are some shots of my Wing Jig. It's 48" long and about 17" deep.
I ripped off three one inch wide strips the full 48" length and screwed them evenly spaced to the bottom of the board. The back fence is another 3" wide strip ripped the full length also and attached to the back with drywall screws and glue. The adjustable sliders are angle iron and screws to hold them in place. The grooves are a series of 5/16" holes drilled through the board, in line, then elongated with the same hand drill.