We're block printing again. After leading classes through this process several times, both the instruction time and the art time has become more efficient. We no longer attempt to affix the scratch foam to something solid as it never stayed attached anyway. The students always ended up holding just the foam piece in their hands, so we just start there now.
This makes finding a clean finger to hold down the paper a little trickier to find, but since the students now expect it, they are better at consciously keeping a finger (or knuckle, or elbow) clean. We've also become a little better at keeping the equipment and the room itself clean.
Until next year...