Configurable calibration test XY grid

This is a very simple SCAD file used for generating XY grids for calibration testing.

Printing note: unless you set a high enough margin print without skirt and brim!

# Customization info
All relevant parameters are customizable - the **bed size**, **margins** (gap between bed edges and the grid), layer height and width and also the **multiplier** that says how many "holes" there will be per dimension. The script also *supports different X and Y dimensions* (in case your bed's height and width are different). Margins for each dimension can also be set separately.

# Example STL parameters
The example .stl is generated for printers with bed size of 200x200mm with multiplier set to 4 (thus generating 16 "holes"), 1mm margins, layer height of 0.2mm and line width (extruder size) of 0.4mm.

# How is the grid generated?
The grid is generated by first creating a big block and then subtracting all the "holes", which (in theory) results in better geometry than adding all the "rows