Now I'd love to work on it full time, but I'd like to keep it free and open source. Do you have any suggestion on how to fund it? Thanks a lot!
So there's nothing new, just google "marketing" and start learning. It will take some or all of your time and there will be a learning curve.
You will also have all of the problems of marketing, like not having any idea if the idea itself just isn't worth money, or if you yourself just haven't figured out the right pitch to the right audience. You'll have to think like your customers/donors, instead of like yourself. If you take it at all seriously you'll start to wonder if you should keep working on what you like or switch to working on what people will exchange money for.
For example, the software that forms the infrastructure of the internet should be an obviously easy pitch for money to support development, or at least QA, but the OpenSSL project got like $2K https://en.wikipedia.org/wiki/Heartbleed#Root_causes.2C_poss...
The only way to get money is to hustle.