[BTG] Better than Graph Paper? Mechanical Test Jig

My twenty-year-old sheet of laminated graph paper has been on my nerves as of late.  The line markings are obviously fading and getting closer together -- It's definitely not my eyesight starting to suck.

Anyhow, I went down the rabbit hole on optimizing for visibility and making the scribe marks relevant to the various checks.  This works for my eyesight and my workflow for collimator walkout, collimator accuracy and table movement etc.  The pop-up "laser blocker" has proven very satisfying (no more hunting for a random object to block the sagittal laser!)

Printing big-n-flat things can be tricky, but I've put together some notes that I hope will help.  I've included a variation that will be printable on a standard size printer bed as well as one for a larger format.  The key here is using two colors, a light color for the top face and dark for the bottom face.  Care should be taken on the color and consider using a matte filament for the top as they can be more opaque.  The top layer is only 0.6mm thick.  3D printers can be more accurate for laying down a "hole" (scribe mark) versus a color detail in a uniform plane of filament.  At least this is my observation.  I can get finer details (at least perceived?) and sharper lines by creating a hole in the top and letting the color below show through.   Consider that a 0.4mm nozzle is going to create lines that are a minimum of 0.4mm.  Whereas the same nozzle can create a "non-line" of some pretty fine detail.  The 2mm circle in the very center for collimator walkout is a good example.  .

If anyone has any "features" that they think would make this better, please share!  I'd be happy to post the .step files if you have scribe marks that work better for you.  (Not going to post the .f3d under any circumstances and make public my disaster timeline and unconstrained sketches!  - the shame!)