1U MMM kit

1U Molten Motion Meter DIY Build Guide

DIY Modules Molten Modular

Thanks for taking on the 1U Molten Motion Meter. It’s a much easier build than the 3U version. All the PCB components are surface mounted and already in place, so all you have to do is solder on the front panel hardware and put on the face plate – EASY!

Here’s my video guide to building the thing, or keep reading for my step-by-step guide.

If you want a quick assembly guide then Befaco has one ready here. It’s what I used to build mine in the video. But if you prefer to follow a series of photos, you’ve come to the right place.


Find a bit of space on a comfortable desk and place everything within easy reach. All you need is a soldering iron and some solder, but there are a few extras I’d recommend.


  • Soldering iron with sponge.
  • Solder.
  • Safety specs.

Useful extras:

  • Magnifier – we are dealing with small components, so some kind of loupe, magnifying glasses or glass would be really helpful.
  • Desktop fan – to blow away solder fumes, particularly if using leaded solder.
  • Steel wool iron tip cleaner – good for keeping the tip of the iron shiny.
  • Helping hands or PCB holder – I don’t use them, but people do like to recommend them to me.
  • Ambient electronic music, obviously. This is going to take a few hours, so soothing generative music will help keep you focused and relaxed.
  • Solder sucker – in case things go wrong.

Make yourself a nice cup of tea. Warm up your iron.

What’s in the kit?

We don’t really need a Bill of Materials (BOM) for this build as it’s just a handful of easily identifiable parts. So let’s look at what you should have.

the kit

Along with the red PCB and front panel, you should have:

  • 4 switches
  • 4 potentiometers
  • 4 lightpipe crowns
  • Power connector
  • 8 jack sockets
  • Red and black nuts for the pots and sockets.

That’s all there is to it as the real components are already on the board.


Power Connector

First, we have the power connector. It goes on the component side of the board and you must make sure that the slot in the power connector matches up with the mark on the screen print. Just drop it in there, turn it over and solder the pins on the back.

Power Connector


Next, we have the switches and these go on the LED side of the board. They fit nice and snugly into the slots and care should be taken to solder them in flush and straight. They sit so well that you don’t need to use the front panel to make them straight.


The only trouble is balancing the PCB when you turn it over to solder. The power connector you soldered in helps with that.

Soldering the switches

Front Panel Hardware

For the rest of the module, we don’t want to solder anything until the front panel is on and secured. So, don’t solder anything until I tell you to!


There are four pots, they’re all the same, and you should find the places for them on the LED side of the PCB. There are two lug holes and then a row of three holes for the signal connections. One of the pots is mounted in a slightly different orientation. Push them in nice and firmly – but don’t solder them!


Jack Sockets

The jack sockets go on the same side. The sticky-out leg is the earth and sets of two sockets share the same hole for this leg, facing each other. Don’t you touch that soldering iron!


Lightpipe Crowns

Getting the crowns in place and pulling the module together with the front panel can be a little tricky. I’ve found the best method to be placing the faceplate down on the desk and putting the crowns into the holes. I then bring the rest of module down onto the crowns and pull the faceplate up to meet it. At all times the crowns are settled in the front panel holes.


Then, as you pull it together, make sure it’s all properly flush.

Crowns, side view

Secure the front panel

There should be 4 red Bananuts and then 4 black ones of the same size, and another 4 that are slightly larger. The larger ones are for the pots – you may need to look very carefully to see the difference.

Starting with the red ones secure the jack sockets and then the pots so that the front panel is firmly attached. Don’t tighten too hard, or you may pull something out of its socket.

Tighten the nuts


Now it’s time to solder the pots and nuts. It’s tricky to balance it because of the pots but see if you can find something to rest each end on. Be careful not to accidentally melt anything with your soldering iron as getting to some of the pins can be difficult. Also, don’t miss the two jack socket legs right on the edge of the board.


Put the knobs on

These are buggers. The knobs go on really tight and take a lot of effort. Turn the pots so they are all the way round to the left. And then place a knob on so that the line points to the leftmost part of the indicated circle. This will help you get it right because you don’t want to have to take the knob off again. I find that once I’ve pushed the knob on my hand I have to lean it on the edge of a table to get the knob all the way down. There’s not supposed to be a gap between the bottom of the knob and the front panel.



As all the hard stuff has been done for you, there shouldn’t be any reason why this is not going to work. Plug in the power ribbon – it can only go one way round – and plug it into your Eurorack.

Plugging in power

When you start it up, it should give a quick dance of LEDs on each channel, and then you’re off.

1U MMM in use

That’s it; you’re all done. Good job!

Any questions then feel free to give me a shout. Although if it’s a technical question about the kit or if something isn’t working then Befaco is your best bet – they are the experts.