It's amazing how popular sushi has become; there seem to be more sushi joints around than coffee shops these days. If it is made with sustainably harvested fish it is probably the healthiest of takeout foods. However take-out sushi is usually served in disposable plastic trays with lids. That's why the designers of Sushecō came up with their clever reusable sushi tray; they estimate that half a billion takeout trays are thrown out each year.
They have come up with a clever design that you can carry flat, and that then pops up to double its height to carry up to eight standard sized pieces and are raising money on Kickstarter to put it into production.
I worry about how many sushi trays something like this would displace; When I get takeout sushi, it is usually pre-packaged in the tray already. I asked the designer in New Zealand, who responded that "it is purchased 90% of the time by the piece in New Zealand. Based on our understanding of the market there is a mix of both "piece purchase" and "pre-packaged fast food" sushi offerings. Globally, we believe this to be the case also." I don't know what the mix is in North America, but suspect it is a lot less than 90%.
However that doesn't diminish the fact that this idea could make a difference. And there is no reason you couldn't put a sandwich in it, either. You can support it here on Kickstarter. Now excuse me, I have to eat my sushi and I don't do it by my computer. More info on Kickstarter