Thanks for the size and ventilation heights. I'll check out the links, too. I've decided my flexy stand will be 24 inches tall, with a bottom, middle, and the top for tv. It looks like the receiver and center speaker will go on the same middle shelf (for the 11" height), unless I design the stand with separations in the middle shelf for height variations. I'm going to use the steel rods and nuts idea and cover them with pvc pipe, that way the stand can be very open for ventilation.
Mogorf, that's amazing what that receiver did. I'll definitely keep that in mind, since I am considering using front attachments to the wood.