Here are some of my ideas so far. Pipe insulation foam engraved with the soldering iron to make a rolling printing block. Works much better with a heavy rolling pin in the centre. You only have to flick it with your fingers so make it work rather than apply a consistent downward pressure.
I used the same pipe insulation foam to put a handle on this printing block. Thought if the kids couldn't grasp, they could just stick their fingers in the centre of the foam tube and lift it that way.
Sheets of foam cut up and glued to cardboard then wrapped up like a brown paper parcel ready for a crayon rubbing.....or paint it, press a piece of paper on top and take a print.
Heavy polythene, cellulose paste and paint. Make marks in it and lay some calico on top to take a print. The school is looking for enterprise ideas, things that the kids have made that could be sold. Obviously there is a wealth of possibility using the kids own hand decorated fabric.