So glad the unicodepowersymbol.com stuff was helpful! We had a lot of fun getting the proposal together.
If anyone wants to submit some new characters, all of our documents are on GitHub https://github.com/jloughry/Unicode
This is a link by the article's author that is intended to make it easier for us to add useful symbols: https://github.com/jloughry/Unicode
I recommend you use it to add any glyphs that you feel are being neglected.
"If you want to get more symbols into Unicode, please use our Open Source Guide."
https://github.com/jloughry/Unicode
Note: glad to see they documented their process. : )
... because you don't have a sufficiently Unicode 9 compatible font to see ⏻, ⏼, ⭘,⏽, ⏾?
You can seem them as images at https://github.com/jloughry/Unicode along with a link to a font which supports it, and a chart which shows browser support.
To propose this character to the UTC (Unicode Technical Committee) you'll need to include as many examples as possible showing the symbol used in running text. Physical objects and logos won't do; you need to show historical use of the symbol in running text (newspaper or magazine articles, books, liner notes, et cetera). Find examples, and we could make the proposal.
We've done it before on HN:
Anyone can propose the addition of a new character to Unicode. It doesn't take $18,000 as some people think. You just need to convince the Unicode Consortium that it makes sense (preferably with solid evidence on use of the character). The process is discussed at: http://unicode.org/pending/proposals.html
I have a proposal of my own in the works to add a character to Unicode, so I'll see how it goes. There's a discussion of how someone successfully got the power symbol added to Unicode at https://github.com/jloughry/Unicode so take a look if you're thinking of proposing a character.