A plywood core structure composed of a medium density fiber board. A medium density fiberboard used as the core in the manufacture of the panel. This is a three-ply construction using a face veneer, a back veneer and the fiberboard as the core. This type of construction tends to produce the most stable panel. Fiber core construction also offers a void free core with excellent machinability. The fiber core with its super smooth surface provides a superior core for finishing the face and back veneer. The only real negative on fiber core construction is the weight of the panel produced. A typical ¾" thick plywood with fiber core will weigh approx. 100 lbs. 2 ply door skin is referred to construction of 1 ply MDF and 1 ply of face veneer.