How do I add a secondary layer to a concave model I have a low-poly model of a purple crystal and I want to add a thin transparent layer on-top of it, I've tried:


Fattening a copy of the model.
Scaling a copy of the model.
Extruding along normals.
Extruding along vertex normals.


But all of them end with the second mesh intersecting the first. If you know something that could work please tell me!
Duplicate the external surface of the model (that will be the internal surface of your transparent layer) add a Solidify modifier to it, set the solidify "offset" property properly (should be 1 or -1) and the proper thickness you want it to have.