This lunch box using the concept of the green house effect. It can warm most food up in less than an hour and it costs less than $10.
Step 1: Materials
A lunch box with a collapsible top compartment: >$5
A space blanket: $1
A square foot of clear plastic: $1
Step 2: Cut!
Step 3: Add the space blanket
Step 4: Put on the clear plastic
Step 5: Glue the clear plastic
Step 6: You're done
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