There are several stages of creating the kato alu, which are plant harvesting, cooking, weaving, decorating, and presenting (Hettinger and Cox 1997, 145). Alu, the root plant, is harvested between May and October because any other time outside this time frame is considered "bad" because the roots are either too small or have already entered the ground. After the roots are harvested, they are baked and then put in the shore of the ocean so that the salt in the water will help the bark peel off. After this, the roots are cut in half and then again and wrapped around themselves and is placed in freshwater from one hour and up to two days.

Now the weaving process may begin and can take from one to six months to complete, depending on the size of the basket (Hettinger and Cox 1997, 146). Most kato alu that are sold are not decorated unlike the ones given to nobility, which can be painted and covered in shells. If given to royalty, the kato alu is accompanied with a tapa cloth, another woven Tongan art, that is placed on the bottom after the basket is filled with coconut oil.

Source:

 Hettinger, Amy, and Paul Cox. 1997. "The Making of the Kato Alu-A Traditional Tongan Basket." Economic Botany 51, no. 2: 144-48.