My freehand illustration skills are rudimentary at best, so I do all of my armorial design using a computer, and I figured I’d post a few notes about the software I use in hopes that it might be of use to others.
(I should note that I’m a Mac user, and wouldn’t even know where to start on recommendations for Windows.)
I use OmniGraffle as my illustration tool, which may seem an odd choice as it seems to be primarily used as a technical diagramming application, but I’ve been using it for two decades and it works well for me. The fact that it imports and exports PDF files means that I can combine armory designs with the SCA’s submission forms, and allows me to give people nice high-quality vector files rather than pixelated images which can’t effectively be scaled up to banner size.
To convert bitmap images, such as those from the invaluable PicDic, I use Potrace. The standard distribution only reads PBM and BMP files, but there’s a Mac wrapper that provides a GUI and adds support for a wide range of file formats, called DragPotrace. DragPotrace only seems to be available from that one Japanese web site, the installation process is confusing (you need to install the regular command-line Potrace first) and the UI is clunky, but once you learn the necessary options, it works great: for most of the images I use, I can just click the “Opaque” checkbox and export the results as PDF.
To convert SVG images, such as the Viking Answer Lady’s SVG Images for Heralds or the Wikimedia SVG Coat of Arms Elements, I use Gapplin to export them as PDFs. The next version of OmniGraffle will add SVG import, which will obviate this step, but in the meantime it’s very useful.
I’ve been working on a collection of standard charges and divisions in OmniGraffle format, as well as templates for armorial design and submission, and hope to share those at a later date.