I didn't want to deal with sewing something like this (I HATE sewing zippers), I went to the local Wal-Mart. In the sporting goods department, I found a soft side soda cooler. It says it has a four can capacity. $4.97. I bought a couple containers of acrylic paint- two shades of green (I have white and a black at home, so I could create slightly lighter or darker shades).
Painting the Creeper- I mixed some white or black paint with the greens I bought to give more color variation, but still have overall tone family match. Then, I painted each square a different shade of green. The nice thing about the pixelated Creeper is that there's no particular pattern or order. As long as I didn't have two squares exactly the same color next to each other, it looked about right.
Once everything dried, I coated everything with a couple layers of mod podge to give the paint a bit of protection. Kids can be rough on their lunchboxes and I didn't want the paint flaking off after a month or two.
I'm pleased with how it turned out, and my total cost was well under $10.