I'm sure this topic is somewhere on the forum, but am too lazy to search right now
I installed a KeelCooler unit from Frigoboat and have been very pleased with it. I used the evaporated bin which acts as our freezer and pretty much items stored directly below this will also be at freezing, or pretty darn near. I like the evaporator bin because of the ease of making ice. I use both the vertical ice trays and I also use a cylindrical, plastic storage bin from Rubbermaid with a screw top lid. I use this for small block ice which I use an ice pick on.
The Frigoboat compressor is whisper quiet and can barely hear it running. I have it on a custom shelf below the existing shelf under the galley sink. This was pretty much dead space for us and worked great running the lines under the stove. I also cut an access door under the stove for running these lines and we store small things here as well.
I was able to buy insulated panels directly from Tartan a number of years ago which I mounted under the lids (don't know if they would still sell these but you could call). You could build your own fairly easy with a little skill.