We painted our balls.
This is actually surprisingly significant and here's why:
For a stencil, I used an old aluminum plate with our number milled into it. I took the first boulder that we had been testing with for the past couple weeks, and pressed the stencil against the foam to compress it so all the edges were in contact with the boulder surface. This is to keep the edges crisp. I was able to do this by myself with my left hand pressing the stencil down and my right spray paining. I took the next boulder, which had never been used, and found that I could not press the stencil hard enough to compress the boulder so that all edges touched the boulder surface. I had to ask a student to press the stencil down while I sprayed, and eventually after getting a few boulders painted, he was showing signs of fatigue and his arms were shaking a bit.
The moral: The new balls are much, much harder to compress than ones that have been used over and over.
