They make em, but probably not is a size small enough for you. Most are large commercial roof top units.
Might make an interesting project though. We'll get right on it and let you know.
Don't forget the small refrigerators made for campers, mobile homes, travel trailers etc.
I have used two of the small used gas refrigerator units in a 7ft high X 6ft wide X 8ft long room to achieve freezing temperatures.
I used 4 inch thick polyurethane foam to construct the sides, top and floor.
The outside had white aluminum paneling for ascetics only. The inside had 1/4 inch ply wood walls to attach shelves to. The ply was glued to the foam inside by painting the ply with one part of two part liquid foam and painting the foam wall with the other part of the two part foam. When pushing the ply to the wall it activates and makes a bond as strong as the foam. I used the natural gas as a backup and assist only and most of the power was solar heated 50% Etheline glycol/water.
I also used 1/2 inch ply on the floor so walking didn't do damage to the foam. I glued a few strips to the celling to hang lighting from.
I used 3 watt LED lamps to reduce power and heat. I had 8 of them and the lighting in the all white room was great.
I used extreme measures to keep the door air tight and with a good thermal seal.
Unfortunately this building/freezer was destroyed in a house fire.
I have retired and moved to the country and will probably build another but I'm thinking of Solar powered Ammonia/water chilling. I have the room so I'm looking at modifying the unit published in the Home Power Magazine.
If your interested in solar powered refrigeration,
start here:
http://blog.wired.com/wiredscience/2008/11/solar-rig-bring.html
I'm thinking large here as in underground Olympic pool or more insulated and frozen or very cold liquid with air ducts/heat exchangers running throughout with thermal siphoning for cooling my home.
Also thinking of using a second under ground reservoir of hot liquid for heating in cold weather. "We hardly ever reach freezing here but it does get cold occasionally."
I have enough 4' X 8' slabs of 4" foam to make another as before but I'm not sure I can't put it to better use.
I'm calculating and drawing. I'm not going out in the winter weather to work anyway.
I don't like weather that is cooler than about 20 deg cooler than my body temp. Grinnnnnn