Here are some photos taken during construction.

Flip Flop Chaos has SMD components on both sides of the single PCB. One of the through-hole resistors is a fix described by NLC and the other is just a substitution for a missing SMD resistor.

A bit hard to see in the above pic, I put two-pin headers where the VACTROL designators are. These are for wiring to the manual slew pots I used as a modification to the circuit. No Vactrols are used.

Wiring

The overall plan for wiring up to the banana jack panel

The PCB is held to the aluminum mounting bracket by 4-40 nylon hardware consisting of threaded standoffs with screws of the bottom of the bracket and nuts over the standoff studs. Some of the boards, such as the Squid Axon above, have large enough jack mounting holes to use for this mounting method. These holes were intended for the switching pin of a Eurorack jack, and are mostly unused. They have an ‘x’ designator on the silkscreen. The jacks are typically on the bottom of the module with board-mounted pots at the top. I drilled out two of the pot mounting holes to fit the nylon studs.

The perspective is looking at the back of the module, which has the 10-pin power header. The power headers are placed somewhere near the top of the module, but in no consistent pattern. The silkscreen marks the negative 12 volt pin as RED. This is good, since there is no uniform direction among the headers on different modules. All of the modules have some kind of reverse power protection, except for the Flip Flop Chaos.

With the pots generally at the top of the module and the jacks at the bottom, it worked out that the wires to the banana jacks were fairly short. Those were wired first, followed by longer wires needed to reach the pots and LEDs.

As shown above, some of the pots used are the 9mm square right-angle PCB mount type. These had to be substituted for the 16mm round pots due to closeness. The wires are simply lay-soldered onto the pins. I put heat shrink on the middle pin to avoid shorts.

The modules that use a separate PCB for the panel parts are connected by 10-pin headers to the main board. This simplified the panel wiring, since it could all be done before plugging in the main PCB.

The Flip Flop Chaos and Squid Axon modules have only one PCB. The photo above details the panel wiring, showing the long pot wires lying atop the shorter jack wires. Notice also the LED wiring. LEDs are lay-soldered to the twisted pair of wired and covered with heat shrink tubing. They simply push into the panel mounted Fresnel lenses.