Designed a basic drafting template in OpenSCAD, printing it now.
Went with a 2mm thickness so I could get some stiffness (will probably reduce), tapers to 0.5mm on the drawing edge. Need to add lips to the insides of the interior cutouts so my writing utensils don’t hop out.
Will probably also change how I translate the cutouts so that instead of running along a centerline dictated by the size of the largest one, the top edge of them all run along a line that’s a fixed distance from the edge of the template. That’ll give me room to add a few more features.