Here's what we ended up with:
From left to right, these three avocados represent a student's first, second, and third try. Look how much better he got in just ten minutes! Amazing!
Another beautiful avocado.
Pear and banana.
Pineapple.
A (very) red apple.
Red pepper.
Wonderful watermelon.
This pictures shows the process. We painted on old transparency sheets, then pressed paper onto our painting, thereby printing the image.