shabbat - Making Sushi on Shabbos

I'm trying to find the status of making sushi on shabbos.

I will ask LoR, but would also like to get info here as well as sources, and use as a guide for others.

Issues I'm aware of / heard of:

• Mevashel - Obvious, let the rice cool first (also pretty painful).


• Boneh - Not really sure why it would be, but heard some people throwing it around.


• Memachaik/Memareach - while spreading the rice. Don't think it applied to ready-to-eat food though.


• Tochen - Cutting some veggies very thinly could pose an issue (such as cucumber) can be avoided by preparing from before.


• Uvda D'chol - So is making a sandwich, or using the toilet. Not sure why this is more than anything else.


• Measuring - simply; don't.

Any ideas/sources would be appreciated.