New method of assembling modules (3D printed monobloc)

Core recently published my 3D printed GPS speedometer project (thanks, guys). I don’t know how many folks are interested in that particular application, but I would like to spread the word about the method I used to assemble the modules into a single unit.

The modules (a Nano, a GPS receiver, a 4-digit LED display and a piezo buzzer) are inserted into a 3D printed oblong I call the monobloc (no soldering). Built into the monobloc are 1.5mm diameter conduits running between pins of the modules. These conduits are threaded with single core copper wire providing the interconnections between the modules as per the circuit diagram. It’s not easy to describe in words but it could be described as a three dimensional PCB.

The method produces a fool proof rapid assembly in a very compact package.

Please have a look at the images in the project page. I’d love to see others make use of the method in their projects – I’m happy to give guidance on how to design the conduits. (What a fun lockdown obsession that was.)

Speedometer project


Looks convenient. Can you give us some idea about the costing?

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Well, if you mean the cost of the making a monobloc for a particular arrangement of components, it’s just the cost of doing a smallish 3D print. It does take a considerable amount of design time in getting the conduits just right. Once the design is done and tested, you can print as many as you wish and they’ll all be perfect. In the case of my speedometer, I’ve done the design work and anyone can print a copy so it’s a close to as kit form as I can get.

Thanks for the interest.


Something I found valuable in this project was making 3-D virtual models of all components. I designed them to 1mm accuracy. They can be moved around on screen to see if they all fit together. If something doesn’t fit on screen then it won’t fit in the real world. Saved many test prints. Also a great way to document the project.


Hi John,

Very awesome idea, I see it being used in Makerspaces where modules are used a lot - like in your project.
The 3D PCB is such a neat idea, you could get it really really dense with some custom designed PCBs!