This contraption is fantastic.  The book has some great ideas and such but my son loves to just take it all apart and make different shapes with it.  Each piece is outfitted with a positive or negative magnet so they don't all fit together but it's fun to get a few and mess around with.  It's been thrown on the floor just in an attempt to reassemble.  Truly a fun toy that keeps his hands entertained when he's thinking.