Have you ever wanted a portable food warmer but didn't want to spend big bucks?
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

I purchased all of these items at Wallmart;

A lunch box with a collapsible top compartment: >$5
A space blanket: $1
A square foot of clear plastic: $1

Step 2: Cut!

Cut the bottom out of the collapsible compartment. This will make it one big compartment. DO NOT CUT OFF THE SIDES! If you want you can cut off the pull thing on the zipper.

Step 3: Add the Space Blanket

There should be a hard plastic box in your lunchbox, you can still do this if there isn't. Cover the box with the space blanket, try to get it as tight as possible. This will make it very shiny :D

Step 4: Put on the Clear Plastic

Cut the plastic to fit onto the lip left by the collapsible compartment, glue it securely with hot glue, or any other glue. After this step you should have a mini greenhouse

Step 5: Glue the Clear Plastic

Cut the plastic to fit the lip left by the collapsible compartment. Then glue it in place. I used hot glue, but any glue should work.

Step 6: You're Done

Leave it in direct sunlight and enjoy a nice warm meal. Close the top to use it like a normal lunchbox.
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Thank you and have a nice day