I have had a large bag of mini Dixie cups (from Costco) under the kids' bathroom sink for a LONG time. Well, it was discovered yesterday by Emily and they have now become their favorite pasttime! They have been building, and building and building - no expensive plastic interlocking blocks, just cheap paper cups! And the nice thing about them - they clean up easy and take almost no storage space. Who knew? (the kids call them their "speed stackers" - although Caleb and Bethany keep saying "bean stackers", cute!) - I highly recommend them!