Ya know, not thinking "Spider boxes" would produce a good google.... Seemed like a phrase that might get all kinds of wierd items. (Thought I'd give it a letsy) And third shot down, gave this result. http://www.laserfx.com/Backstage.LaserFX.com/Systems/Support2.html
It's a winner for the violation forum, get a good look at the schematic and instructions for taking two different phases via two different 5-15p's! (Although it seems this was written for a Euro audiance, I don't think it kosher there either.)

However, I got this.... Now we're talking! Look at this beast!
[Linked Image from bossindustries.com]

Found here , but note, most all of these items are cobbled together items tossed on a frame to be moved easily. But seem well made over the internet...... [Linked Image]

Mark Heller
"Well - I oughta....." -Jackie Gleason