You can build a one piece core also and then split the raw core and then laminate like two skis also. You do not need as wide or strong a press/track/mold/heater/bladder then. You may get a little variation in camber but unnoticebale once you fasten the two halves.

I highly recommend paulownia barn (google them) for US paulownia. it is all the light elongata variety and very well milled and dried