A three dimensional shape core mass is manufactured by machining a ribbon or tape of any material with various slots, channels, or holes of any shape before the ribbon or tape is spooled or layered onto a layering template or spooler. The machining is adjusted so the slots, channels, or holes of any shape extend in a radial or stacked direction perpendicular to the axis of spooling rotation or the plane of layering but with any curve or straight line and with any stacked length. For example, core masses that are manufactured as described are suitable as magnetic cores for high frequency rotating or linear transformers or for rotors and for stators of rotating or linear electric machines when an appropriate magnetic material is used, such as magnetic metal or amorphous metal ribbon or tape.