Pictos
pictos.cc/server
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
That's right. For the first time ever you can now build your own icon fonts with the Pictos Server! It's easy: choose any icon in the Pictos Library and assign a keyboard key that will correspond with that icon. Use as many or as few icons as you'd like, even change them on the fly!