Here's a fun thing I did recently - I created a 12"x12" collage of concentric squares, cut it into 4 pieces, kept one square for myself, and mailed the other three squares to my swap partners.
In turn, I received 6"x6" pieces of similar collages from 3 different artists, with the intention of putting the four squares together to make a new piece of art.
Here's one corner of the piece I created from hand-painted papers and washi tape:
Like a dope, I forgot to take a picture of the entire 12"x12" collage before I cut it up and sent it out, so here's a crappy simulation to give you the general idea:
(This is just that one square digitally duplicated and rotated. The original was made as a single piece and so everything lined up quite nicely)
Here are the pieces I received:
and here are the four pieces all together.
Many thanks to Steph for coming up with the idea and hosting the swap.