This design for a dual camera rig (see Dual Camera Rig for why you'd want to do this) is based on a T-shaped or L-shaped bracket, washers, and two bolts which fit into the camera mounting holes on most cameras.

You'll need:

• 2x 1/2 inch long 1/4"-20 coarse thread bolts (i bought the kind with grippy heads so i can mostly screw them in by hand, then tighten with a hex wrench)
• a thick rubber washer (mine was called a "Chicago style seat washer")
• 2 cameras with threaded mounting holes
• a 4"x4" T-bracket with 1/4" holes (an L-bracket could work too)
• a hex wrench or whatever you need to really tighten your bolts

Basically follow the steps in the images below:

More coming soon... hang on!