I also teach at the elementary level and have students 45 minutes,
once a week, so contact time is an issue with collaborative projects.
I also do an art club after school to compensate, but (and I know this
will be unpopular with some), I treat my lunch/planning period as
additional art time for students who need it, want it, or may have
been absent. I always bring my lunch and don't really want to hang out
in the faculty lounge if there are students who would rather be in my
room working. Of course, if I have a sub or a meeting, the students
just go to their recess instead. Students are always given an option,
too, so it is purely voluntary.