Use this to level your HBP easily with a digital device so you don't have to subjectively go by "feel" with a piece of paper. phineasjw's original leveler had holes that were too small for the magnets to be press fit. Also, the sides next to the magnet were too thin and tended to crack. My version has reinforced sides and bigger holes for easy no drilling press fit assembly. Enjoy! Update 11/24/12; suggested fill changed to 25% from 80%. Lower fill allows the model to deform easier in order to accomodate the magnets. The higher percentage fill version was very difficult to press fit the magnets. I invite you to visit 3dPrintFileMarket.com to enjoy more cool 3d print files. 3d Print File Market is not just another 3d printing website. It is the home of The Original Technology Accelerator App that will change the world.Print at 25% fill, 0.2mm layer height, bed temp 110C, nozzle temp 227C, 1 shell. All else at default settings. Bill of Materials;Use Instructions: http://youtu.be/hgWeew6SmjQ