Make Text Bold от James Zersche

This addon was originally developed for my personal use, but I'm making it publicly available for anyone interested. It's currently in an alpha state—not yet polished for full release—but it functions as intended.

With it, you can 𝗿𝗶𝗴𝗵𝘁-𝗰𝗹𝗶𝗰𝗸 highlighted text and 𝗶𝗻𝘀𝘁𝗮𝗻𝘁𝗹𝘆 𝗿𝗲𝗽𝗹𝗮𝗰𝗲 𝗶𝘁 with the 𝗺𝗮𝘁𝗵𝗲𝗺𝗮𝘁𝗶𝗰𝗮𝗹 𝘀𝗮𝗻𝘀-𝘀𝗲𝗿𝗶𝗳 𝗯𝗼𝗹𝗱 𝘀𝗺𝗮𝗹𝗹 character set.

It may not work on every website. As stated, it's in an alpha state. Future updates will deal with it not working on other sites. It's useful if you're writing a comment or a blog post, and you want to put 𝗲𝗺𝗽𝗵𝗮𝘀𝗶𝘀 on nouns or other key phrases. While writing the description for this 𝗮𝗱𝗱𝗼𝗻, I was able to right click and select 𝗖𝗼𝗻𝘃𝗲𝗿𝘁 𝘁𝗼 𝗨𝗻𝗶𝗰𝗼𝗱𝗲 𝗕𝗼𝗹𝗱 from the Firefox context menu.