I'm new to bento creating, but I've kept up with Pikko's Adventures in Bentomaking blog for ages. That's what originally peaked my interest as well as a desire to moderate my portions. I feel like I'll have no problem with the cooking and creating aspects of bento boxes, but I have one issue that I haven't been able to find answered anywhere: How long can bento boxes be left out?
Fridge and microwave access at my work place aren't a problem, and I know that there are quite a few options for microwaveable bentos. But cold rice just isn't that fun (or yummy), and it'd be a shame to create a hot lunch only to take it out of the fridge 3-4 hours later. This is assuming that you have a basic bento creation of rice, a side of meat and cooked veggies, etc.
So, can a bento be left out for a few hours, or should I just invest in an insulated box/bag/thermos type bento?