Thanks Burning TreeC
The plugin is written in JS not Tiddly widgets -- it a "diversion for my TW Learning path" (or should that be a "meander on my TW Leaning River")
Looking at Evan's work [1], my gut feeling is that it would be easier and more future-proof to work from understanding how Evan is producing SVG images by using the latest version of TW and an approach which has greater potential given they are within the context of the formula plugin
Evan, if you are reading ... what do you think?
Alex