[TUTORIAL] Here is an open source 2 input 1 output furnace i made

https://www.dropbox.com/s/dde3rkox5kyohdr/2Input%201%20output%20furnace…;
Any time you want to add a new recipe, copy the first "if do" and paste, then change the items u want. The first 2 "get a copy of item from slot" are the the items you want to smelt and the 3rd one is the fuel. 
Hope this helped! any questions just leave them here :)