You'd think this would be easy. However, it took about 30 minutes and the assistance of two store employees. While they were looking up what type of base they needed, I moved one of those moveable step-thingys. (I should not be left unattended in a store of that sort.)
Anyway, after the step was painted I realized I was getting hungry, so I made tuna salad with beans instead of mayonaise. It turned out well. I used 1/2 a can of canned beans (rinsed and drained), tuna, mustard, pickles, and the juice from 1/2 a lemon.
It'll be interesting to see how it tastes once it's been sitting in the fridge for a day.