Ihave searched and cant solve this.
I want to mill a 3d form out of polystyrene and make my own shapes.
I make a box, create a plane with x amount of faces on top of box, and when i click finish form its gone. Just the plain box standing there.
Im spanking fresh to 360.
Images came in wrong order…
try hiding the box, the plane maybe a new object inside the box
Please talk like im a 5 year old 
Draw box, enter Sculpt mode and create Plane, make this plane atleast the same size as your box (to the Sculpt plane cover the box plane)
Then go back to Model mode and Modify -> Replace face.
Select source (box) plane and mesh face as target.
Delete the unwanted part of the mesh
Done 
Thanks a looooot 
Scandinavian @HaldorLonningdal ?
Jepp, norsk
Hvor i landet?
Sandefjord
Home made CNC / Fusion360/GRBL/Easel/UGS
Oooo, Fancy Larvik her
