Thanks! :D Like a tutorial? So the plywood is screwed to five wooden spines, and the spines attach to perpendicular ceiling joists using joist hangers, simpson ties, and angle iron from an old bed frame. For the holds, you pretty much get a flat surface using a miter saw, drill a hole with a drill press, shape it with the miter, and then sand to comfortize. A router can also help with shaping if you have one. I wish I had a photo album to go with this but I didn't take too many as I went. Anyway, cheers! :)

Ayy *finger guns*