Siapo uses the bark of the u'a (paper mulberry tree) as cloth. The bark is carefully peeled off the tree in strips and then the inner bark is separated and scraped clean. It is then pounded until it widens into a larger size. The pieces of cloth go through a process where they are pasted together to make a larger cloth then decorated.

Siapo are decorated in two ways: either freehand or by taking rubbings off a relief pattern carved into a plank or board. The dyes are made from a variety of plants and trees and an earth ochre called 'ele. Freehand-decorated siapo are called siapo mamanu. The motifs used usually represent plants and animals.