Probably too diffuse still, you would need a focal point in front of the bulb for it to cast a recognisable shadow I think? Because the reflective dish would be bouncing light at all angles around the stencil, including inside the intended shadow. You need something exclusively pointing light in a focused beam.
The flashlight on my phone seems to be a pretty decent for this kind of thing, so whatever led and design that’s got going on could work.
Oh that could totally work actually with the parabolic reflector. I’m not sure about the leds, I think there might be a lense involved in the phone to direct the flash to a certain radius. It didn’t reverse the image or anything so the focal point must be at the lense itself. Anyway, I’m sure with some messing around we could get such a batsignal torch.