Its not open source, but after trying a number of these tools (as a total noob hobbyist) I found Diptrace to be the most intuitive and they do offer a freeware for hobbyists
Diptrace isn't too bad, they also have a cheap version [1] for non-commercial use if you need more than just 2 layer boards. Only thing is I wish they had a native OSX version.
https://diptrace.com/buy/non-profit/