Parametric grid cube to verify linearity of the entire printing / building volume of a RepRap/3D Printer.This is a parametric grid cube: best edit the .scad (OpenSCAD.org) file direct with your printing/building size and create .stl from there. Note: all numbers in .scad in mm (size x/y/z, spacings and grid thickness)Defaults: 200mm x 200mm x 200mm with 20 spaces (or 21 struts) with 1mm x 1mm profile.See also: http://reprap.org/wiki/User:Spiritdude#Quality_ControlHistory: -1.001: spacing per axis definable (xn/yn/zn), see 2nd picture xn=20, yn=10, zn=5 -1.000: first version