Make a relief out of 3d model I am a complete blender beginner. I have a 3d model and try to make a relief out of it, by putting it on a flat rectangle, so that it is suited for 3d printing (only the z-height should vary, so 2.5d not 3d). As the data is noisy, I need to cut some data away. I tried to do this with vertex dissolve. However, then I end up with the following situation:

Black and green is the contour of my object and in gray you see the rectangle I put my object on. However, I would like that the object goes straight down to the rectangle, meaning the faces of the red line instead of the green line.
Another possibility is to simply erase the vertices. However, then the border of my object looks like this

and I would like to have the border set to the same height. However, I don't even know how to select the border
A relief can be generated using shrink-wrapped plane over the object.






Procedure (tested on Blender 2.79)


Add the object to blender and a base plane. Position the object over the plane.

Add another plane over the object and the plane on the bottom.

Subdivide the plane until the mesh is relatively fine. 
 
Apply the shrink-wrap modifier to the object. Set the mode to 'Project', set the target to the object name (in this case 'Suzanne'), set the auxiliary target to the base plane (in this case 'Plane').