Due to the two big capacitors I used the inverted variant of the design (thanks Yuriam for the second revision!). The print came out great and the printer works on a much lower noise level right now.
As Yuriam suggested, I only used support for the upper-right fixation part.
Initially, I didn't use screws to fix the fan as it can be seen in the picture.
In the meantime, I've cut M3 threads into the corners of the cover and fixed the fan with matching screws.