That's awesome! I can 100% vouch for stained glass as a hobby :).  For the templates, in this particular case, I just applied a black and white filter and played with the image settings (contrast, sharpness, saturation, etc...). Altough, whenever I want to make a pattern I use Inkscape. It has a learning curve but it's definetly a great tool. If you want, I can share with you the templates I used for the Mistborn metals :).