A coopered door is simply one that is curved: concave, convex or, when you combine the two, serpentine. Adding a coopered door can make an amazing difference to a common square cabinet.
There are a few ways to achieve a coopered door. The easiest is to find a board that is naturally cupped. Since most of us aren’t so lucky, a second way is to cut the curve out of a thick piece of stock. With this method, the height of your door will be limited to the resaw height of your bandsaw. As well, when removing more wood from one side than the other, the wood may move or check. The most effective method is to cut several strips out of a single board and join them back together again to form a curve. This method is ideal for making any size of door, and for preserving grain graphics or colour.