Flat hole profile or intersection from solid body

You need to create it as sheet metal.

Chris, CSWP
SolidWorks '20
ctophers home
SolidWorks Legion

As ctopher said, it needs to be sheet metal.

Yes, you are working with a tube. Don't sweat the semantics. You need sheet metal feature functionality. (I do this all the tie for flexible circuits.)

If the part is sheet metal-friendly (i.e. uniform thickness and perpendicular edges), you can convert to sheet metal without re-modeling the whole thing.

Once you are in sheet metal mode, you can make a normal cut, which will be unfoldable.

You can try the surface flatten tool You need a premium version for that command but here is a way out, use the seed feature from this post Do not delete the flatten surface feature but roll back and add your feature or you can insert your part into it. And then edit the flatten surface feature and select the surface you want to flatten.

Deepak Gupta
SOLIDWORKS Champion and Expert
SW 2022 SP0.0, 2021 SP5.1 and 2020 SP5.0
Boxer's SOLIDWORKS Blog