Betaflight is cool, but I wanted to try something new - my first KISS build.
It's 4S but prepared for 6S.
The goal was to build the counterpart to my 5" Rat Quad (https://rotorbuilds.com/build/27916 ) -clean, lightweight and without zip ties...

It flies very smooth and powerful, but there are still some tuning issues to work on.

Primarily I planned to use the Karearea TOA 2207 bi-turbine motors, but they are out of stock at the moment.
Therefore I used the Xing2 2306 2555 KV and made it 4S but prepared everything (cap, spike absorber, 12 V BEC) to change to 6S the day the TOA 2207 are back in stock.
The Marmotte frame is great, but I don't like the proposed mount of the AirUnit, so I build my own adapter (see photos).
This adapter is, what I was able to manufacture within one hour without special machinery. It could be more handsome and more lightweight but it works and the weight of 5 g isn't too bad.
Why I used aluminum? First I'm a bit old-fashioned and not so adored to 3D printing but the aluminum will also support the heat dissipation!

I decided to use FETtec components for the ESC and FC.
It was an odyssey to get one of these FETtec FCs...

I'm always keen on finding some custom solution for every build.
On this build I outsourced the spike absorber and cap to a cage for the XT60 plug.
Furthermore I mount the Crossfire antenna at the tail... I'm not sure, if this is a good solution - what do you think?
To illuminate the machine room, I used two LED strips, mounted to the underside of the top plate.

To get the weight below 400g, I used titanium screws where possible.

Weight with props: 399 g
AUW with 4S 1500 mAh: 580 g