Side panels were actually built before I put plastic on the feet. I first cut out styrene panels that were exact matches for each foot. I layed each foot on the styrene and marked it with white primer so they would match each foots irregularities. The plastic cut very easily with those orange handle scissors that everyone seems to have. The plastic cuts very nicely if you leave it in the sun first for about a half an hour to warm up. It looses it's brittleness. The inner panel was made from 1/2" MDF with a rounded routered edge. Then the "bread sticks" were made from sections of 1/2 round moulding. I copied Richie S.'s design for mounting clips. After the MDF panel is glued to the styrene I calked around the join with wood glue twice to create that sort of one piece look. They came out better than I expected. As you can see by the flat backside this is why my axles could not protrude any on the sides that meets the side panels.

Here's a good shot showing the added on extension panels with the notches cut out and one of the connecting plates painted flat black to make it invisible between the knee plates. You can also see the platforms with the casters from the inside.

The feet are bolted together with three large bolts layed out in a triangle pattern. I used an additional nut on each one to maintain proper space between the feet. Location of the connecting bolts is not very critical as long as they are positioned so that the nuts can be easily reached for tightening. Since so much of this project is your own design always keep in mind "what will make maintenance and repair easier for you, in the long run" when you are designing a part.