The only thing i can say is that i use one carton size (rectangular) for all the needed heights, size ca. 40*30*20. For example: DSS-1 is at the bottom, the carton below stands upright. Behind that is the JP8000, both cartons are lying. Completely in the back is the JX8P, carton below is lying, the other one over it upright. The DSS-Keyboard is so seen at 50cm height, the JP8000 ca. in 70 cm, the JX8-P in ca. 90 cm. Ok, i could do another construction for making even the DSS lying at 70cm and the JX8P to 1 Meter, but the construction is good for me, how it is now. I put (because of the depth) those Synths, which i program less, into the backround, cause it isn´t very easy to program them at this depth.
It was for me the best solution, cause i didn´t had the money to buy keyboard stands for (now) 10 "normal" Synthesizers. And in addition: One can move them easily
Stef