Sorry, don't have a picture handy, but I used the same arrangement of GoPros as the commercial product linked above (although this is the first time I've seen that product!): two portrait orientation, two landscape orientation, then one up, one down.
Found the way to get the lenses as close together as possible was to physically stick the cameras to one another using heavy duty double-sided sticky tape. Did it in such a way that I can access all but one of the SD cards, that one I download using the USB cable.
I sandwiched in a piece of G10 fiberboard that extended out a bit (out of view of any lenses) and provided hang points since the rig was suspended. I haven't thought much about how to attach a pole to the set-up so it can be carried or attached to something, but I'll get to that eventually. The trick will be to hide the axis of the pole between overlapping areas of the frame as long as possible.
The main cost of my setup was about $5 for the roll of tape.
Chris