Want a super simple macro lens for your phone without shelling out big bucks? You can use 3D printing to assemble your own! Shapeways user Lens42 has created a 3D model for a slide-on iPhone lens — all you need to do is have the 3D model printed for $11 and to attach a $4 glass lens from Surplus Shed (part number L4471) using some superglue. If you have something other than an iPhone but know your way around 3D modeling programs, you make some measurements yourself and have a custom 3D model printed.
3D Printed iPhone slide on Macro Lens [3DFuture]