Ds 2 is going on a trip with his nursery and needs a packed lunch. Looking something easy to clean as he might not eat everything being a toddler, but that I can also put little ice packs in as the weather is to be very hot. Ideally something not too big so he can carry it himself as well! We do lots of day trips but we've always used a cool bag so it would be nice for him to have something he can carry himself if we go out walking and reuse it. Any suggestions?