One of first issues I stumbled upon when preparing this project was whether I'll be able to create custom PCBs in a fast and precise way. There are three reasons why I needed such solution:

1. QLBRD modules have limited internal space, in most cases off-the-shelf components just could not fit in. Moreover, spaces aren't regular but mostly curvy. Also oftentimes first prototypes do not fit well or have missing features as we, humans are fallible . Thus the best choice is to have fast prototyping line for custom boards (on flexible base) and resolder elements on them;
2. I have no fully blown lab as making things is my hobby. Out of simple solutions available for guys like me none was precise enough to give decent results. UV sensitive paint + etching solution works best, but often results in small defects due to side light scattering. So, I decided to try something else.
3. PCBs can be ordered with professionals, but I live in Sweden where distances aren't negligible, things aren't readily available off-the-shelf even in online shops and delivery times aren't the shortest (I still wait for Blufruit LE to come). 

So, I decided to give engraving a try. In a matter of minutes I turned a spare 3d printer nozzle into engraving tip using a piano wire I found stuffed in mess. The rest is shown in the video. And results are better than expected.