Hi Martin, if you reverse the direction of the picked points that for the axis that will also reverse the direction of the revolve.

So like currently you're picking the start of the axis at the center point and then the 2nd point for it upwards along the z axis.

Instead pick the 2nd point downwards on the z axis to reverse it.

It would be a good idea if it did support a negative angle though, I have put that on my list to look at.

- Michael