The reason for doing it was I'm interested in comic books so I just did a search for various superheroes and see what they had. The Bat Signal seemed simple enough and not too complicated so that's why I decided to do it. I was able to find some of the items around the house, others I had to buy
or borrow from my Dad's workplace. I got the USB notebook light from Maplins, the clear plastic sheets from the college shop, the foamcore and hot glue gun from my Dad's workplace (I also got the smoldering iron there but ended up not losing it). Everything else was found around the house. I also didn't stick exactly to the recipe as I realise I could do something in a different way. Instead of a shampoo bottle cap, I used a bigger cap for a cleaner and drilled and hole in it. The hole was big enough to fit the bulb with cutting up the wires. I just used the hot glue gun to keep it in. I didn't want to risk accidentally cutting a wire when it was fine that way.

I then wrapped tinfoil strips around the top and stuck them on with paste. Originally, I didn't know where to get foamcore, so I tried to make the support yoke out of wood. This proved to be rather difficult and I ended up snapping it while trying to saw it from a plank. I moved onto making the base, getting some loose change and sticking them under one at a time with the glue gun. I left it till the next day when I got the foamcore. I cut out the foamcore with a blade. I stuck the yoke onto the base and then sprayed it with paint. Let it dry for a while and then gave
it another coat. Unfortunately I didn't have any black spray paint so I stuck with what I had. Eventually I stuck the top onto the yoke. I cut out a circle of the clear plastic sheet and stuck it on the top. I printed the Batman logo from the the internet and stuck it on the sheet.

Other uses could basically having different designs and stencils on the light, not necessarily just the Bat signal.

Reference:
instructables.com/id/USB_Batman_Spotlight/