There are 3 courses here for 3 string players. The 3 string slide course and 3 string fretted course are for beginners and the 3 string slide blues course is for more advanced players looking to improvise and play the blues.
Currently The Groove Workshop is specific for 3 string slide players although the concepts discussed there are applicable to any instrument. Once you've done any of the beginner courses this workshop will be useful. The upcoming slide workshop will be relevant to both 3 string and 4 string players.
There are 4 eBook packages for 3 string guitar: 11 Christmas Songs, Blues for RJ and The Chord Book are for fretted 3 string while the 17 Blues Turnarounds are for both slide and non-slide players.