I need ideas for building a cage for two rats..?

Well, I made my own rat cage, simply cause I could make a roomy cage that was cheaper then a large cage from a pet shop. Here's how I did it, I bought five 1ft by 4ft planks of water sealed wood (water sealed so no pee or anything like that would be adsorbed by the wood and ruin). Three of these were cut in half and used as the different levels. Then i got a circle saw and cut reasonable sized wholes in the corners of the different levels (i had the wholes in different places on each level to make it more entertaining to get up and down for the rats). I left the back open and just put chicken wire that's 1 inch by 1 inch and stabled that down (A LOT OF STABLES) then i made a door out of wood and chicken wire and i have a bottom and top latch (they are trunk latches) and thats about it all held by screws and stables lol. My rats love the space and it looks better then a old wire cages in the living room