Does anyone have any plans for building grow beds from plywood and 2by2's and 2by4's?

we can't get prefabbed beds here and to ship them in from Australia is expensive and the customs tax on items like that are 100%.

I do have 6 mil plastic. but any others waterproofing ideas would be great. I could epoxy the wooden boxes.

Anyway, I need to see some plans I would like to build 4' X 16' grow beds. no gravel all floating beds.