X & Y Calibration Ruler Pointer

Clip this on to your hot end nozzle for a precision pointer.
Now you can easily see exactly how much the head/bed is moving during your calibrations.
WARNING: Do not attach while your hot end is warm, or the plastic will melt, warp or possible fuse to your hot end.
I've sized mine to a ubis hot end that came with my Printrbot Simple 1r05, but because its small, it likely to fit most, even if it flexes slightly...
It's not a precision print, but its a precision tool... Gets the job done,