Mirroring

[Oneiromancer]

How do you mirror a selection around a certain edge (for instance, if you want to draw an intricate symmetrical object)?

 

[Oneiromancer]

Thanks, useful hint, that. But not for mirroring. This rotates the image, so you'd only get an upside-down mirror image. It's not symmetrical.

 

[Mike Read]

Edit > Transform > Flip (Horizontal/Vertical).

I'm fairly certain if you've highlighted a certain area it will constrain itself to where you've highlighted, but have never checked personally.