All kit parts.
Use a flat cutter to cut the top of the plastic housing off, starts from the corners on the side of the screw terminal.
You can use a flat cutter to wiggle and break of the plastic.
When the top is gone, you can break of the flap im cutting in the above image (i am "cutting" to what it is that needs to be removed, you can just wiggle it back and forth and it will break of in 3 moves or so. i do not cut this part, just wiggle).
I use two layers of paint cover tape to dampen the click from the relay, otherwise it clicks to hard. In the above image i show how far i (sort of) put the tape into the relay.
Here you can see the tape inside the relays.
Strip the ends of one side of the ribbon cable and tin them. The first and last two wires are twisted, they are GND and +12V. The center 4 wires are the relay signals, they should not be connected together.
Put the rubber grommets in the PCB front pannel and then the bolts thru them.
Add the spacers and bolts. And cut of the pins from the header of the relay board.
Jump the little jumper with some solder to it is sure to stay connected, you can leave the jumper on.
Add the blue cover PCB (its for protecting the relay flaps).
(I replaced the 470 ohm resistor with a 1k resistor, the 470 ohm resistor is the blue resistor)
Solder the components to the PCB.
The Vactrol has polarity, on the PCB silkscreen there is a text indicating where the short leg of the LED goes.
Solder the other 4 components.
Put all components in, make sure the PCB's are strait, then solder all.
Connect the relay cable and solder the piezo wires.
Add things to make sound with to the flaps, you can solder to it while the module is powered, because it is isolated. But dont solder when the flaps are moving, its not a good idea.
Now its ready, you can tune the filter as you prefer with the 10k trimmers and the 200k trimmer is for pre amp volume.
More ideas for variations below.