Help making light shine through a shape or design, like a cutout or stencil

[Evan Glen Tindle]

What I'm saying is basically you have a black background, and a shape is cutout of it and light is shining through. Like a jack-o-lantern, but that's not what I'm making. I've seen a tutorial with text but I'm doing a shape with much thicker lines than text. I'm not looking for any kind of masking, because the light should create rays and glow over top the black background. If you don't understand what I'm talking about, the thread titled "Need design advice - cut out text that light shines through" is very similar to what I'm looking for. I've tried many different techniques but can't seem to get anything that looks realistic. Thanks