So here is the second half of my project to defrost my lunch (or whatever else) utilizing old computer parts.
Warning: Be certain that if you are planning on replicating this project for your own use (which is fine with me), take extra special care when removing the circuit guts from the inside of the power supply unit. There are large capacitors and other assorted things that can quite possibly give you an electric shock, the likes of which you have never experienced. This shock can cause serious harm and quite possibly, death if you are not careful as to what you are doing. I will not be held responsible as this is strictly an experiment of my own and I am a certified computer technician who is well aware of the risks.
The first plan of attack I had was to gut an old computer power supply (PS) and use the box as a sort of plate/ air chamber defroster. I left the fan inside of the unit and attached it to the switch which is also already installed in the power supply. On the top plate, I attached an aluminum heat-sink from a processor and even used the 'transfer paste' between the two surfaces.
When this is assembled again, the fan will pull the air in from the ventilation side of the PS box, pull it across the heat-sink and out of the front of the unit. When you put something frozen on top of the (PS) box, the cold is transferred to the box itself and absorbed by the heat-sink. Pulling room temperature air across the heat-sink will help to warm it up.
I tested this device and found that it worked pretty well as expected.