I bought some of the Crayola Fabric Markers for this, and reading the instructions I note that it says one should iron the fabric, or if not possible then throw it in a cloths dryer for half an hour.
Well, obliviously I'm not going to put a rangefinder in a dryer for half an hour.
So what have others done to cure the marker material? Use a hair dryer? Just let it dry for a few days?
Seems to me from the description on the package that heat is almost required to get satisfactory setting of the material.