Every time I try to extrude a face on a plane it has created this hollow shape. I don't think this used to happen and its happening on all my files. How do I fix this? I want a solid to be formed from extruding. I know I can fill the faces but I'm not sure if its an issue with my settings that is causing this?
$\begingroup$ I have tried recalculating normals but that hasn't fixed it :( $\endgroup$– antihistamineFeb 8 at 15:50
1$\begingroup$ because the other face needs thickness as well, extrude both, then extrude only the left one $\endgroup$– moonbootsFeb 8 at 16:01
If you extrude a face, it won't keep the initial face:
Unless you extrude or all the adjacent faces as well (or unless you extrude a mesh with one unique face):
If your object has already thickness, as you can see it won't keep the initial face either, otherwise you would need to delete it every time you extrude: