First I took off the doors, hinges and handles and cleaned it up. Then I painted the top, sides and doors leaving the back, inside and the edges of the doors unpainted. If a painted surface rubs against a painted surface you get peeling and/or sticking. Then I poly'd the whole thing once and a did a second coat on top.
Cabinet : $8
Paint : $8.47 (It was in the "oops" paint at walmart which is %50 off!)
Polyurethane & brush : FREE (We found them in the tool shed when we moved in )
We have 3 fish tanks in our house. This one is a 55gal fresh tank with a million little community fish. We also have a 10 gal. saltwater with clowns and coral. And a 2 gal. fresh with an underwater frog in it. And thanks to this cabinet, all the "stuff" gets to be in one place! :)