Yesterday i managed to create this shape that is similar to a teardrop.
I then mirrored it on the Z axis using the mirror modifier like this:
But the shape is hollow from the inside and that creates a problem when I render it as glass, because instead of passing through a solid object, the light simply passes through 2 glass planes.
Is there a way to create a solid object from a hollow one ? I haven't been able to find a sort of "Fill" function that does that.


3D modeling tools always create "hollow" hulls. There is no such thing as a "solid" object. If an object appears to be solid it's just an illusion created by using the right material shaders.
As always, it would of course be important to know what the purpose of your model is (still render, animation, game engine asset) to give an appropriate answer.
– metaphor_set Sep 04 '16 at 11:21