On the top of the page you’ll see the edit button and next to that is the share menu popup button along with the Archive button and Comments button. The share menu popup button is available via Fandom Developers at https://dev.fandom.com/wiki/ShareMenu
I'll look into that. Mix was called StumbleUpon a few years ago but it merged into a new service and reformed as Mix. Its early days but the service works a lot like Pinterest. Is there a Pinterest button I could add to the share menu script as an alternative?