1/2 of model with inverted normals. I want to work with it, not to fix it

Back is open surfaces. And it’s mesh. Makes it very difficult to do anything. Would be nice if it was actually closed. Hence why the pictures are only the front view.

I wish the back would have been closed. and half the model had flipped normals which i had to repair. also the model i thought was to thin, more height (depth) would make it easier to work with. The file names were not clear, should be labeled .stl, ,obj etc