IMO
The wall hung idea is an interesting one, but it's too shallow.
A standard wall cabinet is only 12" deep. If you try and do a frig that's similar with the necessary insulation on the back, and the door, and door shelves....too small.
Where as the floor standing "standard" oversized 30" deep refrigerators we know too well, is TOO Deep. Plus the bottom 24" to 36" of a refrig isn't efficient for use.
Small frigs are about 19" wide x 18" deep and anywhere from 24 to 36" tall. 1.4, 2.6, & 4.5 c.ft are the typical sizes available in both frigs and all-freezers. These days they have glass shelves, a lighted interior, and reversible doors.
Setting them on top of a standard 25" counter top, even two of them side by side provides ideal refrig space. Not too deep you'll loose things in the back and not too shallow you have to be concerned if something will fit. They're also inexpensive, easy to move, and energy efficient.
