Computer Program For Templates

Hello All,

I have a question for everyone; can anyone recommend a good program (preferably for free) that I can use on a Mac to make templates for painting locomotives and such. Currently I am painting a BQ23-7 in Atlantic Coast Line colors (even though they never had them) and I want to make a template, on the computer for accuracy, for the front and rear silver arcs.

Thank you so much,

CJ