Because it's hard to see these parts of the stands in the photos, I figured I'd include some new photos for you, Bimota, so you could get a better idea of how they were made.
Since a solid point of contact is pretty important with a jackstand, I carved out the ends of the stands so they would provide the best points of contact with the crash bars. I didn't want the round bars to just sit on top of the 2x4's; it would be too easy for them the slip out of position if the bike was jarred while I was working on it. The cutouts on the tops of the supports, in conjunction with the crossover bar, lock the supports in position.
I shaped the ends of the stands with a large spade bit in a drill, a handsaw, a rasp and a chisel. The way they're shaped would depend on the particular shape of your crash bars, so my photos are more of an example than of a specific guide of you you should fit the supports to your particular bars.
I'm almost embarrassed by how rough this project is. It was a rough and ready design that I knocked together in the middle of a maintenance task, with the intent to refine the design later. They worked well enough though, and I already had enough other projects going, that I left them as-is.