If you try to make hand-rolled sushi or chirashi sushi in your kitchen, you may find the rice is too sticky or something doesn’t turn out just right. Likely, you are using the wrong container for preparing the rice. In this case, you’ll need a sushi tub or “oke” in Japanese, which is essential for making delicious sushi rice. However, though having one of these is much better than not, the materials used in the product still need to be considered for getting the best results.
Generally speaking, sushi tubs made of wood have a humidity-regulating effect and absorb and release moisture from the rice to make your sushi rice extra tasty. The sushi rice also does not get soggy and achieves that desirable fluffy texture. Another great advantage of wooden sushi tubs is the aroma of the wood will transfer to the sushi rice, softening the harsh smell of vinegar and enhancing the flavor of the rice. Of course you won’t get these tasty effects with plastic or other materials and as you know Japanese cooking is all about these subtle delights so in the end, you're going to really want these advantages from the tools you use in your kitchen. Wood sushi tubs also appear much nicer than anything made out of plastic when used for serving chirashi-zushi at celebrations.
Although wooden sushi tubs all look pretty much the same, there are notable differences in the materials used for the wood and outer hoops of these products sold online and in local retail stores. For the wood, we recommend either getting one made out of sawara cypress or momi fir. Then for the outer hoops, you’ll want to either go with copper or a plastic called polypropylene. Below we’ll discuss the differences between these materials.
Sawara cypress wood produces a very pleasant aroma and will stimulate the appetite when combined with the flavor of vinegar. Furthermore, the fine grain of this wood prevents it from shrinking after drying. It is the ideal material for this product because this wood absorbs the absolute perfect amount of moisture from the rice. 
Japanese momi fir is a less expensive material choice but still has good water absorption properties and does not require any special care, so sushi rice tubs made of this material are easy to use and maintain. It still has an aroma that will be more subtly but still sufficiently transferred to the rice.
Copper hoops are very strong but will expand and contract a little, which is ideal for quality wood like sawara cypress that is not prone to distortion.
Polypropylene is considered to be a relatively safe plastic and is a great material for the hoops of sushi rice tubs because they are soft and flexible yet durable and robust. These are ideally used with lesser expensive woods that tend to shrink a lot.
If you do not have a sushi rice tub yet, here are two different ones which contain these recommended materials.
TIKUSAN Hangiri Sushi Rice Mixing Tub Copper Band with Lid
TIKUSAN Hangiri Sushi Rice Mixing Tub PP Band with Lid
