Yeah ! Another real DIY'r
If you are building from scratch (where do you get scratch anyway) you will most likely be building a "linear" supply, that is it will not be a switcher. I'm not sure what power supply a refridgerator would have that would be of use unless it's one of those "solid state" refridgerators that use the peltier junction heat transfer pumps.
Here are a couple of links that may help.
http://ludens.cl/Electron/Ps20/Ps20.html
http://www.reconnsworld.com/power.html
If there are any "computer recycler" places in your area, you might want to give em a try and ask if they have any really old big printers you could rob some parts out of. Transformers, capacitors, full wave bridges, and maybe even some bigger steppers.
Enjoy
Steve