Need help solidifying this model

Alright, so I have a mask model for a project of mine, just the problem is, I can’t seem to get thickness on it, without the mesh going crazy.

Of course, I made this model myself, and what I really wonder is if it has to do with the way its built, or if there’s another way, even if its longer, for me to add thickness to it, if not through solidify. Other modelling programs give me similar results as well, so it has to be the way its built, but it just annoys me that I don’t know how to build it in the right way, that blender or silo 2 allows it to thicken, shell, correctly.

Its really important that I give this mask thickness, else it won’t look right, and just thickening its rim isn’t enough.

mask.blend (502 KB)

The normals are pointing inside and outside, Ctrl+N in edit mode to recalculate them, it should solidify fine.

To add thickness to my objects, I usually just go to edit mode, select everything, press E to extrude without moving the extrusion, then resize the extruded faces to make them slightly larger than the original model.

Thank you ramboblender, that worked! :3