Housings generally come with handles to which one adds arms.
I posted a couple of examples in this thread: http://wetpixel.com/forums/index.php?showt...mp;#entry236686
I use a blend of ULCS, TLC, Seacam, and Subtronic arm components. These all use 1" balls enabling mixing and matching across brands. I use the same stuff for diving but without the TLC tray on the bottom (which is there to provide stability on the uneven stream bottom).
When diving it may be useful to connect two arms (when using two arms) with short straps that have a fastex buckle between them (available in dive shops). The trick is to make it easy for someone on the boat to pass your housing to you after entering. Sometimes just using a built-in handle (housing held side-ways - left or right side up) works better.
The attached pic is a few years old. I had been in HI shortly before I took this picture and still had the housing arms configured as I had used it there. The two arms are connected via one of these straps. There is also a neckstrap which I generally do not use. I was trying it out as a way of carrying the housing around in a stream leaving my arms to move or hold branches etc.
