Note however, that I called steam bending an art. It takes experience and practice to consistently produce sled parts in the shape you want. Be prepared for broken pieces and sometimes a lot of frustration. But when you have mastered steam bending, it becomes not only a practical technique but a captivating one as well. Wood, even when cold and dry, can be both compressed and stretched.
Steam softens and plasticizes the cellulose in the woods structure.
Therefore, build a little extra bend into your forms. Boiling water will also work but steam is more practical because larger pieces of wood can be plasticized more quickly and easily. Steamed wood also absorbs less water so it dries more quickly and can therefore be removed from the form sooner, typically after 24 hours. Obviously, if the wood has to be held in its new shape for 24 hours, a form of some kind is necessary. The wood can be held in place by clamps or heavy twine until it cools and dries.