I haven't done backdrops since I taught elementary but we made large
frames that were stretched with muslin and then we treated the muslin
(can't remember right now. some kind of prep. We did use tempera paint on
the treated muslin. They stood up in a folding way were about 6 ft tall.
This is 25 years ago! But I know we didn't have any acrylics to use then
in the elem school so we had to have used tempera. We might have used some
kind of sizing first like wallpaper paste? I did the enlargements of
things and assigned students to paint certain colors. Sometimes elem
student can't do very big enlargements. Another idea to enlarge Take kid's
drawing and do a transparency of it either by tracing with the
transparency sheet and a marker or by taking a copy through the copier.
Then put on overhead and project and trace! Good luck. Fran