Is there any way to modify the level indicator component to be a custom shape or have a custom shape do a vertical fill?
The level indicator is made to be simple. We did that so you can put vector graphics or draw your own graphic on top of the level indicator. Take a look at this how-to:
http://www.inductiveautomation.com/support/usermanuals/ignition/using_symbolfactory.htm
on Symbol Factory tip #2. Hope this helps.