I've made several based on the instructions at 24FC. I live in Maine, USA so the winters are cold and snowy and the spring and fall rainy. Mine usually last about three years outdoors before they need replacing. I use hemlock, which is locally available and rot resistant. Cedar would be excellent but it is very expensive. For the pad I use a thin foam strip (usually a can cooler cut to fit) and wrap it with duct tape. It's not pretty, but it works.
There's a pic of it on my site http://seisui.weebly.com
. Ignore the pic of the guy with the bad beard and the serious samurai face.