little pet play pen

I knew we needed a large area for the the kids and the rats to run around on the floor and play freely.  I wanted to make or buy a play pen type enclosure with walls high enough that they would not be able to clawl under or jump out.  I did see an nice option online that was flexible plastic that you can roll up tighly.  The problems were cost and it was not high enough (only 2 ft tall and about $45 before shipping).  The other option was to collect cardboard boxes and make our own.  That envolves a lot of time and energy trying to find boxes that are the same hight and enough of them.  Not to mention a lot of cutting and..... just a lot of work.  And again, it's nice if it's not ugly.
So finally I settled on what I think is a great idea, and preferable in every way to the others.  I've bought 32"x40" white foam board.  It's slick on the outside and heavy enought that I don't think they will be able to get under it.  I would be shocked if they could jump over it.  So I've set the boards up sided by side (long ways on the floor) and taped the edges together with that cute colored Duck tape.  I spaced them out on the tape leaving enough space in the middle so that it can be folded up easily accordian style.  By making it this was you can add as many boards as you want, and still create as small or as large an enclosure as you want each time.  Also, you can fold it and put it away neatly.
The best part is the cost.  Each board at Hobby Lobby is $5.99, but with the 40% off coupon I got them for $3.82 a pc.  The Duck Tape is about $4. 
I only have 4 boards put together so far, but here is what it looks like.  I plan on adding at least 2 more, and maybe a few more later.