What's the cheapest glass?

Yourself

L1: Registered
Jun 13, 2009
30
1
Limit the ability to see through multiple layers, that's the only way to help the cost of translucent materials.

For example, by using func_areaportalwindow entities, or laying out the geometry of your map in such a way that windows don't have a clear view through other windows. Like being able to see across your map through 5 buildings because their windows are all lined up.