The Conrad Hoffman protractor is a PDF so while printing it, have a ruler ready to measure the actual print. Increase or decrease the print scale by as little as 1 to 2% and re-print it. It's best to print it at a professional print shop with plotter type printer usually used for printing engineering and architectural drawings because they're better calibrated than multi function printer-scanner-copier machines. Sometimes a printer's calibration will be perfectly okay in horizontal direction but a bit off in vertical direction (and vice versa). In such cases go to a different print shop. Yeah, I know it's a lot of trial and running around but that's the fun of creating your own protractor:)
And regarding mirrored surface for aligning the cantilever, use any small mirror. It works perfectly as long as there's sufficient lighting in the room.
And regarding mirrored surface for aligning the cantilever, use any small mirror. It works perfectly as long as there's sufficient lighting in the room.