Since switching to using TJ Thompson cleats, I've created several cauls for top and bottom cracks. The top crack cauls are for X braced guitars with two tone bars between the bridge and the bottom of the guitar. After seeing how much easier it was to align cleats to the cracks with these cauls, I made the various caul design files parametric so they could be adapted to different brace locations, tone bar widths, and spacing.
TJ Thompson Guitars offers "crack corrector" cartridges that you may prefer for your crack repairs and can be found here: proluthiertools.com
The video and image below show how to take measurements of the tone bar locations and widths using the "brace locator". The measurements are entered "as is" to the parameter table of the caul you select. The design takes care of adding clearances on either side of the tone bars or brace. There is also a parameter for the magnet hole diameter in case you want to use different size magnets than the ones specified below from Amazon. Another source of magnets is K&J Magnetics, kjmagnetics.com who offer a wide selection of high quality magnets.
If I encounter a top crack with edges that pucker up, I use long StewMac sound hole clamps to gently clamp the top and bottom cauls together. Check out Tony Lewis's video Splitting A Sound Hole Clamp In Half for a nice demo on how he does it. dev2.loothgroup.com
For printing I use PLA and an infill of 15-20%.
