I'd suggest that an easier option would be a series of points. With four points on a piece of paper you should be able to do a full calibration of the printer. Since they're points you can just leave the laser pointing at each one while you adjust it until it's exactly on target, then move on to the next one. With lines you'd have to make it move really slowly and keep track of where it went off the correct path.



Apart from that, another worthwhile option would be to have software calibration. Hardware calibration is always a pain in the neck; you adjust one thing and something else changes unexpectedly, you adjust the wrong thing the first time, or parts shift over time and you have to start again. However, if you printed out a plastic cube (or whatever the Peachy prints when you send it a cube) and measure the lengths of each edge then it should be possible for the software to create a transformation matrix that ensures all future prints are 'perfect'. The results might not be quite as good as a perfectly (hardware) calibrated printer, but for the vast majority of things they'd be more than adequate.