Let’s start with this raspberry pi 4 aluminium heatsink/enclosure, I prefer these over a traditional plastic enclosure and over traditional metal enclosures because these can also act as a passive heatsink. Going with just a plastic enclosure isn’t gonna work for you unless you plan to keep the raspberry pi idle all the time and going with a metal enclosure would also require installing some heatsinks and or cooling fans. Depending on what you are running on the pi you might get away with just passive cooling from one of these.
This one apparently is designed specifically for the pi4 so the aluminium islands that are supposed to contact the chips have exactly the right shape and size for that. It’s important to search for one advertised for the model of pi you have to get that perfect fit and optimal cooling. This one is for my homeassistant server, I will likely install it on a DIN rail so I will probably use some zip ties in the beginning and then depending if I ever feel motivated enough and have the time I will also design and 3d print some kind of DIN rail mount for this enclosure. Same as always links for all of the products shown in this video will be placed in the description below so do check them out. Oh and I know raspberry pi boards are hard to find these days, if you are in the EU, last time I ordered mine from WELECTRON.COM checkout their website to see if they still have any in stock.