Pictures of my SEQ V4 version made with the standard Wilba Frontpanel milled by "Schäffer AG" (Germany) and a custom made 5mm acrylic case lasercutted by "Formulor" (Germany)
This device was assembled with the guts off a Trust Sight Fighter USB gamepad to which were soldered the keys from an old ps/2 keyboard. stuffed into the base box of a Cheetah Annihilator joystick.
The top where the keys are mounted is from a vinyl plank used for kitchen flooring.
For the lack of high precision tools for cutting the key holes, some of the keys are slightly misaligned. I like to think one day I will re-do it properly.
With Pure Data, then all controls are converted to MIDI and forwarded to Logic. As the buttons are not velocity sensitive, the Pure Data patch as the option to randomize velocity in a specific range to give it a little bit of a human feel when recording.