So, FamilyFun suggested this instead of lunch baggies, plus it is tons more durable so it will keep your items from getting smashed.
Take a gallon milk jug and mark off three of the sides small like in the picture and one tall side up to the top. (FamilyFun shows a milk jug without the divets, if yours don't have them, even better, you have to fiddle with it if you do.)
P.S. My poor hubby's coworkers shake their heads in pity that I send the man to work with lunch containers made from trash, but I promise there is a reason behind my madness! Tupperware would do the same thing, look prettier and clean up easier, but my hubby's lunch pail is too small to accommodate a bulky sandwich container. That's why we use this, it fits.