The original SignPrintf source, an hMod plugin from 2010~2011
This is the original source code to SignPrintf, from 2011. I had thought this to be lost to time until digging it up in December 2017.
I make no guarantees about how well this would translate to anything besides hMod... but hey, if you try to port it, please let me know! I'd love to see this old beast rising again.