For all my years (35) of teaching art "down at the elementary," I have
always instructed the students to put their names and room # on the edge of
a piece of manilla paper, which is cut the same size as a cardboard base.
They set their clay pieces on these to dry overnight. Then I carve the names
on the bottoms of the clay when it is leather hard. The cardboard base makes
a good carrying method, too. The students do not get the clay until their
cardboard/manilla identification set-up is complete and on their table
space. I use the cardboard bases over and over.
The comment about being able to read one's own writing better made me
laugh. When I started out teaching, I once saw a primary student's painting
signed with ..
ael. It took me several days to decode that one. :-)