This is my main phin guitar. Although it has a few flaws, I love it because it has smooth bamboo fretting, it's plays really well and the pickups sound great.
You can see from the picture that unlike a standard guitar, there are fewer frets. The spacing looks random and at times too large; this is intentional. It allows phin players to constantly stay in key and makes improvisation, which is very important in Issan music, much easier.
The fret system on the phin is the same that is used for the Sueng, Chapey Dong Veng, and several other Asian instruments.