I automated 10 of my interior doors. When I built my house, I had it pre-wired at all the interior doors for door contacts. I have been holding off on wiring them because of the cost per input for my Security/Automation panel (HAI).
Following the lead of @sipvoip I purchased a Pokeys57E that has 57 digital input/outputs on it that can be read with modbus. The device costs about $55 - really hard to beat on a dollar per input basis.
I installed contacts in many of the closets and some of the bedroom doors. The contacts drive automated lighting.
One thing that I struggled with was how to get a combined ground for use across the digital inputs. @sipvoip used a wirenut - I was really worried about connections coming loose with wire nuts. I ended up buying some screw terminals with barrier strips. At first, I was going to use one screw terminal per ground, but I can get 3 or 4 securely.
Just if someone is looking for a cheaper alternative: you can get PCF8574 modules with 8 DIO and I2C interface for less than $1. Adress set by DIM switch to combine up to 8 of those in a I2C network.
Connected to a host (e.g. Pi Zero W, ESP32/ESP8266 board or any Ethernet capable board) you come to a fraction of the $55 for 64 DIO channels (plus the DIO channels of the host controller).
Sure, here you are for a Raspberry Pi example and here for an Arduino based one. This one describes the use in ESP Easy.
Connecting multiple nodes via I2C bus electrically is shown at Wikipedia.
If you get the following modules you can simply make a chain of them (each with a different jumper setting i.e. unique I2C address).
If you get another type with a different address space (PCF8574A) you can even add another 8 of them for another 64 DIO.
It works the same way for any other I2C capable host controller.
Searching for PCF8574 and your MCU of choice should give you plenty of results.
@Kim_Andersen haha, the music was just as a fun gemic In normal use everything moves at the same time and no music. I still need a blind for the window in the kitchen. But you are right, it is still a bit bright without the last blind
I understand. Although I´m not a projector fan myself. I like the big size screen, but the good picture quality requires alot of darkness, which is very hard to have in a ordinary livingroom. Insted I have a big (65") LG OLED screen, which infact isn´t big enough. I would have prefered a 85" or bigger insted.
A small trip to Denmark will solve that small problem
They actually are available in Germany. They donât show on their website, but in most stores you can already get them. Shouldnât take to long until you can buy them online as well.
⌠However, the room seems quite too lit for projector use??
In normal use everything moves at the same time and no music. I still need a blind for the window in the kitchen. But you are right, it is still a bit bright without the last blind 
I understand. Although I´m not a projector fan myself. I like the big size screen, but the good picture quality requires alot of darkness, which is very hard to have in a ordinary livingroom. Insted I have a big (65") LG OLED screen, which infact isn´t big enough. I would have prefered a 85" or bigger insted.