Working with Sculpty

[Cjankowski]

Hello all, so I wanted to take a dive into using the sculpt tool in wings today. It's quite a neat little tool. Awesome little addition wings thank you I was playing with all the effects but seems I cannot get my brush to invert. Maybe I am pressing the wrong buttons? I really like this tool as I would like to use it on a project for inside scultptris and wings. Any help would be greatly appreciated and thanks a bunch in advance!