How to add a single image lightbox?

Good work @Oliver, @TimPlumb + @Mary!

Agreed it would be nice to have a class input built-into the image edit.

We'll be adding the latest Redactor 3 in Pulse 5.1. In this the new setting imageFigure allows to turn off wrapping images with figure tag.

e.g.

$R('#content', {
imageFigure: false
});

So you could certainly use this Oliver then or just be aware as Tim says above