Where to find, install and activate the Flat Surface Machining plugin.
Issue
For PowerMill 2021 or older, the 3+2 flat machining plug-in is an add-on that requires an external download and installation. This plug-in, once installed and enabled inside PowerMill will aid the creation of multi-axis offset flat finishing, raster flat finishing, and slice area clearance toolpaths.
For PowerMill 2022 and on, a toolpath called Inclined Flat Finishing can be used to achieve a better result.
Answer
PowerMill 2022 and newer
PowerMill 2021 and older
The Flat Surface Machining plugin is an unsupported external installation that is not recommended. No future development is scheduled for this, it is recommended to update to the latest version of PowerMill to access the proper toolpaths.