On my youtube channel, I did a series of videos showing how to model and make a working bat signal from a USB clip on spotlight. These are the files I created during the project, including a whole separate version, and a few different examples of the lense.
This does require the lamp to make it into a completed model (you can grab one here https://www.aliexpress.com/item/4000689973129.html
And you can follow along the design and finishing process here! https://www.youtube.com/watch?v=m34hyT23qUQ