Some maps don't seem to have enough, or sometimes any compass rose, maybe they only have cardinal directions or a grid but no magnetic declination information at all, now you can easily add as many compass roses as you like, accurately with this stencil and a Sharpie fine tip pen. This is a big deal if you are navigating by map and compass or using landmarks on a map to try to get yourself or a radio contact un-lost or reoriented.

This was inspired by me seeing an American evasion chart, a military map for downed airmen or cut off soldiers which has not only several forms of navigation and several compass roses on each side but also local and general survival information, how-tos for carried survival gear, and first aid instructions; even current drift rates at sea.

This is a .scad file to compile a customizeable compass rose stencil in OpenSCAD for 0.4-0.5mm tip pen, compiling options for extending cardinal lines and half protractor for use with parallel rules(then turn it around and align to do the second half of the rose). I have also included what I imagine to be the most commonly desired STL file output options that people might choose to speed printing for those not familiar with OpenSCAD. Even a novice should be able to follow my comments though if they understand how to comment or uncomment lines of code. You can change the size of the 'spokes' and switch to mils or whatever you need as you have the easy to hack annotated source code.
60mm circle rose with points extend 32mm at 5deg lines, 34mm at 10 deg, and optional 36mm at cardinal points or 64mmx64mm cardinal lines across the compass rose.
I wanted this to add compass roses all over my maps, including National Geographic Adventure and Reise Know How polymer waterproof and tear resistant maps. Any open water area or waste area without too much topographic change is a perfect area to add a compass rose.
Use extreme caution to note the map grid and if it points to true or magnetic north. Once you have the compass rose applied be sure to add a magnetic declination line with a ruler, mark your true north arrow with a five point star. I have updated (v1.1) the stencil with these marks.
For now I will be printing in ABS but I think I will email it to a friend who can print both a half and a round stencil in clear(translucent) polycarbonate. I have cut the thickness to 0.5mm(v1.1) to save some plastic and make cleaning up easier. Makes me wish I had a laser cutter as I believe that would be perfect for making these stencils.
CAUTION: Use extreme care to properly align this compass rose correctly or making other changes to a good map. A failure to do so could lead you or someone else to become lost or worse, perhaps even 50-100 years in the future. So use care and take your time, perhaps even take a bearing between two landmarks on your map and verify it online and with a protractor on your map. Date your declination and note the angle off of true as there is drift over the years especially at the most extremely affected areas where the information is most important.

v1.1
Added a Star stencil ( thanks to Juan Gonzalez-Gomez (Obijuan) [email protected] which is under the GPL) http://www.thingiverse.com/thing and an arrow stencil to mark true and magnetic north. Also enlarged the line size to 0.7mm as my first printing was pretty narrow. Made stencil thickness 0.5mm. moved out al of the lines to make them extend inwards at different lengths from a 68mm circle rather than radiate out from a 62mm circle with a cardinal cross inside.

I am now thinking that it would be fun to also have a set of north star finder/pointer stars stencils with Cassiopeia, Ursa Major and Minor, maybe also some finders from the imaginary 'south star' for use in southern celestial navigation too.
(update)Here is that Polaris finder diagram stencil http://www.thingiverse.com/thing:1709126
OTOH I am learning that silk screening and a laser printer might be easier than all of this. Still in a case where you have a 3d printer and nothing to silkscreen with this is great, and the stencil can live for decades in a desk drawer ready for quick use with a pen or pencil.