Microsoft handed those (well, not the 'double' one) out a couple of years ago as Silverlight/Expression swag, pretty sweet toy and fun to play with. You can ma

Microsoft handed those (well, not the 'double' one) out a couple of years ago as Silverlight/Expression swag, pretty sweet toy and fun to play with. You can make a continuous folding 2d variant with paper fairly easily as well, though I don't know for the life of me how it's called.