Trouble Importing Non Closed Polysurface to Revit

I’ve converted the 3ds file to a 3dm to import into revit- I need the file to be a rfa file. I have closed the meshes into polysurfaces but the back of the chair won’t close. Is there any way to get it into Revit without having to redraw the surface so it’s a solid? Thanks in advance.

Link to file -

Hello - the object has non-manifold edges, I assume that is what Revit does not like - use ShowEdges > NonManifold to locate these - you’ll have to extract the extra internal faces and delete them - might be a bit tedious. It might be more effective to work on the mesh and then convert again when duplicate faces and non-manifolds have been sorted out on the mesh.