I was really bummed to find that the PCB is almost exactly the same size as a Eurorack front panel, which means it's to big to fit between the rails. :(, But, there is pleanty of room below the PCB at the back to add a bunch of 3.5mm jacks (with some case drilling). I'm really digging the size and addition of the 1 octave tact switch keyboard. Most synths this size require an external keyboard for control, but this I can grab and play while tweaking on a modular patch. Fantastic!