Case for Raspberry Pi2 and Pi3
This is the case for the Raspberry Pi2 or Pi3 itself. If you have a Raspberry Pi4 then please have a look here.
Top case variants with slot for the Raspberry PI Camera and DSI dislay as well as one with extended 40 pin GPIO slot which also fits the connectors of 40 pi extension cables:
A cover for the GPIO slot can be used to protect the GPIO slot when no HAT or display is being placed on top of the Pi.