I am sure the Snap-On guys will scoff at me, but I have been thinking a filing cabinet would make a great side locker. Although it is probably not wide enough for your hot pocket warmer.
Just gut the drawers, add in some shelving to desired height, and get a flat piece of steel (for the door) and an a full length hinge and you will be done. You can even reuse the lock if you desire.
I really want to make one for my items in blow molded cases, hammers, power tools, and anything else that eats up too much of my drawer space.