Ahh, here's a picture of the spanking bench from the Gathering. One of the folks who attended is starting to put up pics on Fetlife. Two people took most of the pictures. I'll be getting them on a CD at some point, when they have time to download them all. For now, here's a sample.
Note the slot in the back for the balls, with the loop of rope hanging down. On the right side down near the floor, you can just see a support bar that goes front to back. It's got four different sized wooden semi-circles stored on it. The semi-circles each have two posts that fit into two holes above, completing a circular hole to trap the balls. You have to pick the semi-circle piece that best works to trap the balls. Then, that loop of rope secures the wooden semi-circle in place.
The result is a subby who ain't goin' nowhere! lol