Another set was both delivered with 2 equal sides, for the left side instead of 1x left + 1x right. With the effect that I was allowed to just mill the openings for HDMI, audio and power supply via Dremel itself. Well in acrylic luckily not the problem.
But the work with the Dremel is anyway required because the side parts are relatively thick, so that power supply connector and HDMI connectors can not be sufficiently inserted in the PCB and thus guarantee secure contact. Thus, the plug must be extended generously not be blocked by the side panels several recesses.
The opening for the Micro-SD card is also dimensioned too small and the Raspberry board is not firmly locked on all sides in the case. With the effect that in certain circumstances the Raspberry board is held exclusively by the Micro-SD card into position for which she is most certainly not intended.
For people who do not want to clean up the manufacturer's sloppiness, I can not recommend this casing sure.