I actually have a stained glass insert for my case. I am currentley working on getting a more "old church" looking window now but they are damn expensive
my friend does air brush and he is freaking good. he painted his case and it is blue white and black flames. he painted the window and everything. painting a window isnt that hard. if its going to be one color then use car paint u can find it at a auto store near u. it doesnt flake or crack. using a brush will suck. you wil get lines and streeks in it. u want to spray.
That's not a bad idea at all, that way if you screw up, you just get a new transparency. It'd be a lot cheaper then replacing the whole window if you mess it up