Sometimes it can be useful to add a gap in a tool mount to allow a flange to pass through without a collision.

As shown in the image below, the flange collides with the punch. Click on the Add Gap switch located under the advanced section of the punch tool dialogue. This option will only appear if the tool mount is long enough. A small section is displayed in the panel, with a set of interlinked inputs to set the left margin, right margin, and actual gap. Since the sum of these three must add up to the tool mount length, editing two of these will set the third one automatically. The proposed gap is displayed as two orange lines traced on the bend mount.

Click the OK switch in this sub-panel, the gap will be created, and the collision error is now resolved.