Diy Wet/dry Filter System

[Daveo]

I am currently looking to build my own Wet/Dry Filter system out of a standard 10g. aquarium that will be the filter for a 20L or a 29g tank (not completely decided on which way I will be going yet). Basically I decided I wanted a wet/dry filter for the added volume and for that extra little bit of filtration. I figure if I can spend $80 on a canister filter I might as well get what I want and DIM (Do It Myself!) and spend a whole lot less in the process.

Does anyone have any knowledge of Wet/Dry filter making? I could use all the help I can get.

Thanks for the help!
Daveo