I used locking miter joints and pocket screws to hold the cabinet walls together so it can be disassembled if needed for moving.
There is a 1" gap all around the outside of the chest freezer to allow for air flow that will be assisted by a 115v muffin fan. Also, from the back side view, you can see a gap between the collar pieces for running electrical to the temp controller.
Here is a view of the muffin fan installed by the compressor. Air will be pulled in from the far side of the cabinet and pushed out the open bottom of the chest freezer.