The traditional fiber for Bilum bags was made from the inner bark of the wild tulip tree and other readily available natural materials. First the bark is soaked in a stream or the sea for up to 8 months until the material that binds the bark twine together rots. Then the bark is dried and the strands of bark are separated before the woman will rub the bark with her hand on her thigh to produce the strands of twine.
There were many methods used to traditionally change the colour of the twine fibre. Sometimes the twine was rubbed on a white stone and the result was pure white. Another method was to soak the twine in mud before weaving. Slate stone, orchid bark, roots and jungle grasses were some of the other materials used to produce dye. Burnt shell was often used to make the dye fast. Some special seashells were also crushed to produce a dark red dye. The end result was often striking especially the earthy colors. Unfortunately it is becoming more difficult to find a genuine traditional bilum.