Please post an image of what you are trying to do. That will make it easier to comment.
Depending on what you object is, perhaps you can (1) switch the view so it looks flat (clicking the faces of the cube in the upper right hand corner to rotate your object), and then (2) create a new plane, (3) use line tool to trace over the silhouette of the object, and then (4) PATCH the silhouette (one of the SURFACE commands), so you fill the trace so that it's a flat piece (no thickness)?
Or do you want thickness? (So, say, a house a squashed down to a silhouette of a house that is, say, 1 mm thick?) I've never done this and I'm not at my computer that has inventor fusion on it, but perhaps you could (1) select the object and (2) EXTRUDE the object (a command under SOLID) (I'm not sure you can do this with your object) to create a really long extruded object and then (3) create a plane which is parallel to the EXTRUDED object but some distance away; (4) on this new plane, create two rectangles with a gutter 1 mm wide between them, (5) use EXTRUDE again (under SOLID not SURFACE), set it to CUT, and then select two rectangles and EXTRUDE through your really long extruded object, thus leaving a silhouette 1 mm thick.
Again, I'm not at my computer with IF on it, but if step (2) doesn't work (EXTRUDE to create a really long version of your object), I wonder if you can select your object with the SCALE command. There is a button on SCALE (I forget what it's called) that either (a) gives you one arrow, meaning that you are scaling the entire object in all 3 dimensions simultaneously (e.g., making a sphere into a bigger sphere); or, if clicked, (b) gives you three arrows that let you scale in only one dimension - so you can pull an object and make it longer but not taller (e.g., you can pull on a short cylinder and make it longer, but not increase the diameter).
Hope that helps.
Frank
