I have a box, and I am looking to make it hollow using the offset and extrude tools. However – instead offsetting the edge and then pushing down the inner section, I would like to pull up the outer section. However, it won’t let me select just the outer section. If I tap on the outer section, it simply selects the entire top of the box.
Any advice on this? Thanks!
tap the surface of the box, chose add plane. Project the outer face you want to extrude and project it to the plane. Then extrude that into a new body and then union the 2 bodies. You may have to hide the first body to select and extrude the projection.
Thanks! But it’s a little more complicated than I described…
In the picture, I’m trying to pull up the outer edge of the box. Projecting it onto the plane gives me the same problem… I can’t select the outer area, so it won’t project onto the plane.
Sorry, not seeing/understanding outer area. Oh wait you mean the 4 outer edges top of the box?
The section colored with red in the pic below. Just trying to extrude it up… not sure why it’s proving so complicated! Thanks.
Select the outside edges and you should be able to project them as well. The outermost edges of the body. Just the edges not the face.
Once you have the lines projected, make the main body invisible or selecting the desired face isn’t easy. Once you extrude the new face make visible and union the 2 bodies.
This works great, thanks! Shame that you can’t just select the area and extrude 
There might an easier way. Kind of counterintuitive but it works. Other programs a face can project to next sketch IIRC.
