Is anyone aware of a source for the kinds of stencils, templates, etc., that would be helpful if one wanted to try his own hand at emblazonments?
The truth is that all you really need is a pencil, paper, and source material. There are plenty of books to be found at the library which depict coats of arms. Copy them. Start basic. Don’t worry about drawing every single charge and every swirl of the mantle. Get used to drawing the helmet, and the shield. Practice, practice, practice.
For me, some charges require practice. Recently I did an emblazonment for Andrew Vidal, whose arms include two heraldic eagles. I spent several weeks looking at reference material, and imitating the work of others before I was prepared to actually design my own heraldic eagle.
Eventually, you will work your way up to coloring. You will have a great deal of choice in this matter, the decision is yours to make. Some prefer digital images. I use the computer in the design process, but I prefer to paint in watercolor. However oils, pastels, crayon, textiles, ceramics and so much more can be used for media.
Rendering a blazon into an emblazonment also takes practice. There is an on-line version of Pimbly’s Heraldic Dictonary. http://www.digiserve.com/heraldry/pimbley.htm I recommend that you put it at the top or your favorites list. You will be referring to it frequently.
Thanks for your counsel, Eric!