How to create a 3d relief from a complex 3d model

[wendorfAJ88Y]

I have a body (a model of a building with spires) that is turned on its corner. (See included file.) I also have a sketch with a projection of the model. What I want to do is create a 3d relief by "dropping" the body down to the projection (by filling in all the empty space between the projection and the body, including the spires). In the end, when you look at the model from the top, it should still look the same as it does now, but when you look at it from the sides, it should look like a nice, solid body that is 3d on the top, and flat on the bottom. I hope that I'm explaining that well.

When I try to extrude from the projection to the body, it keeps giving me errors, even if I do an offset with the projection to make sure that it is completely in the "shadow" of the building. I can't figure out how to do it with a loft, because the body doesn't have one nice flat area that I could use for a sketch. If anyone can point me in the right direction, I would greatly appreciate it!

[laughingcreek · Accepted solution]

in theory you would us solid sweep to do this.  unfortunately solid sweep fails on such a complex body.  in general fusion sucks at manipulating mesh models (and solids created from mesh models) like this.  you might get there eventually with some labor intensive work, but there is no guaranty.

OTOH, this is rather easy to do in a program that is made for working with meshes.  I've done this type of thing rather easily with blender for instance.

[wendorfAJ88Y]

Thank you for the quick and helpful reply! I haven't worked with Blender before, but I did find some steps that will hopefully work. Wish me luck.