I've been dying to crack out the blue spraypaint. Failing to find Optimus Prime Blue, I went with ... azure lake mist... or something equally as obscure. To simplify things, it was the only colour of Krylon H2O blue that I could find. I painted the foot, the only complete part that is to be blue.
After doing the foot, it was time to pay more attention to the leg. I made the leg WAY too wide. I would've had to walk like I was feeling the ill effects of a 4 day hot pepper eating contest (read: squatted big time) so I glued the side walls for the leg a little bit inward such that I could cut them off afterward. I tried to line them up with the 'foot shroud'.
One neat thing about this was the cans of spray paint fit PERFECTLY in there as spacers. The whole deal was very wobbly so the cans fixed that situation.
I then sliced the excess of the INNER leg off and tossed it aside. For the OUTER side, I cut carefully as I could use the excess to make Optimus Prime's fender. Simple straight cuts, and one at a 45 degree angle down the edge of the smaller piece previously cut off.
I did that for both sides, here's how Optimus Prime's leg looks so far.
The only remaining piece of business was to glue the back on, I don't think I need to explain that. (Hint: It looked like a big 'ole rectangle.)