Originally Posted by willwren
I'd try STEAM. Heat and water. Then use some kind of clear coat on the BACK side to help it hold it'* shape. Just guessing here.
I agree with willwren here. You can use putty or something pliable to make the letters/graphics. Steam the fiberwood/board and make sure it becomes pliable. It should be wet before applying it to the mold you've made. Try it on posterboard for testing using hot water, let dry. The clear coat is an excellent idea to maintain it'* integrity. Good Luck and let us know how it turns out!