PS4 ControllerBox

so Ive looked into mesh mixer and made it to a solid body. i saved as an .obj and went back to fusion.

when i try to cut it but it won’t let me to select the imported mesh. i thought i may have to convert the mesh into Brep but it then throughs an error saying it hast too many faces.

what do i have to make the new model cutable?

a big thanks to all of you already bringing that far and in advance for all the advices.

Foxx