I saw this on Etsy and could not resist. Cut it from 3mm MDF after first spraying the sheets with Rust-oleum spray paint from the big orange store. Solid white piece, cobweb next, then the orange bat and spider layer with "HALLOWEEN" letters stuck on afterwards. I used superglue to hold it all together. Finished thing is 12mm thick. 
Took me about an hour if you don't include paint drying time.