I liked the idea too.

I absolutely love this idea, and would like to suggest some additional symbols alongside what @BeatlJoe listed. Adding a 90 degree curved line, a diagonal/ line (with left\ and right/ variations) and a circle (with solid and "outline-only" variations + transparent inner area for outline circle if possible) all with a few sizes for each (a minimum of SM, MD, and LG versions would suffice) or add the ability to change the sizes with a slider of some kind would pretty much give us COMPLETE creative freedom! I also saw someone mention there's already a "Size Slider" mod out there? Maybe just add compatibility with that mod for sizing if this mod and the slider mod are not already compatible?
After pretty much finishing this entire text, I noticed this thread was created just over 2 years ago. However, I still feel its worth mentioning. So if this has already been done/added, or there's already another mod out there just like this (that actually works) then I apologize for the pointless novel. Although, If there is a mod out there like this, definitely let me know!