So I did! Here are the pictures he sent me of a design he found online:
It has a bunch of holes, so you can zip-tie the pedals in place, and places for the cords to go too. Once I had the drawing, I printed it out poster style to the right dimensions, and cut it out to show my brother-in-law, as it was pretty big. Wanted to make sure that's what he was looking for. It was.
I taped it to the plywood I was using, and got to work with the jigsaw and sander.
P.S. I had to make those saw horses before I could get started on the project, because I didn't have any. I also needed them for something else anyway, so this just made me get it done.
I couldn't find anything similar to the metal brackets that were in the original pictures, so I ended up cutting some 2x4's at an angle, and then cutting those in half to give me two supports for the top piece. Also, I didn't get a picture of it, but I only printed the paper template once, so I had to use it twice. Once to cut out the lower deck from the plywood, and a second time to cut out the upper level piece (I had to cut up the paper template to do it).
I routed the edges and sanded them a bit so some of the top layer came off, making a cool-looking feathered edge to it. Then I drilled. I drilled a TON of holes. I did count, but I forgot how many there were. It was around 150-200. Yeah. I drilled all the ones in the picture here by hand, before I was able to borrow a friend's drill press for the rest. That made it a zillion times better.
I finished it off with a coat of natural stain, and a couple coats of polyurethane, the night before we left for our mini-family reunion.
My brother-in-law was pleased. He's already making good use out of it. I showed this to a co-worker who plays as well, and he got really excited, wanting to do something like it for himself.