Just put together my kit last night. Maybe a two hour build, including my embarrassing mistakes in Teensy programming. (Yes, when installing Teensyduino on a Raspberry Pi, the udev rules are important.)
I used a Teensy 3.2 that I already had put full length pins on, so it stands a bit proud from the socket, but that probably made it a little easier to attach the two non-socket connectors underneath.
The MIDI output works like a charm; the synthesizer is a lot of fun if a little noisy. If I use it for any kind of performance it'll be through a processing chain, so that's not a huge concern. I look forward to digging into the source code and playing further.
Product works well my son ( 14years) is using it the whole weekend, had a little difficulty to get the Hex file into the teensy but managed in the end. Volumn is a bit low , i had to add a small amplifier to give it a bit more boost.
I enjoy in this product! Using as midi+audio which is great for pocket, just plug in headphones or whatever and play! sound of harp/guitar is beautiful! Even if you are not skillfull in playing you can play, because when you miss octave, sound dont sound harsh, you can just continue :)
p.s: don`t make my mistake and try to join this on your own, there is some additional work, follow the manual on hackaday! :)