I started building to most complex module so far for my modular: the Klee v2 analogue sequencer designed by Scott Stites. It is a very different sequencer compared to other designs. You can use it as a “normal” sequencer but it can do much more…
The complexity of the build lies within the massive amount of wiring that needs to be done to connect all LED’s, switches and potentiometers to the PCB’s.
I ordered the PCB’s from electro-music.com. The front panel, designed by Thomas White, came from The Bride Chamber.
The picture below shows the front panel with all controls. 
Here the front panel as seen from the back.
And these are the two PCB’s for digital logic and analogue circuitry.
Let the fun begin…