Here's an unusual little product designed to mount several different accessories. The Movo Magic Ball Multi Adapter features sixteen 3/8" female threads, comes with 6 rods each with multiple 1/4" & 3/8" female threads, and comes with a set of 1/4-20 to 3/8 Male|Male threaded adapters.
Should be a good way to mount a bunch of stuff over a light stand, tripods, or rigs. Excellent accessory to pair up with variable friction arms. It's a bit unconventional but I think the parts alone are worth more than it's retail price of just $19.99 + FREE Shipping. Find it (HERE).
Movo Magic Ball Multi Adapter w/ 1/4-20 + 3/8" Threads + 6 Rods for Accessories