A minimalist case for the Pluto Nano SDR I got off Aliexpress (the one that has 2 USB C ports and 2 antennas, photo included for reference). The heatsink is exposed for cooling, the USB ports and antenna sockets are fully accessible, and the buttons can still be pressed with the case on. Assembly is just press-fit, no screws or anything required.

(Note: I got the heatsink dimensions wrong on my print but I couldn't be bothered to print again so I just fixed it with a dremel - I have increased the area for the heatsink in the uploaded file so hopefully fixed)