Please excuse the Number of steps, its easier then you think.
Warning - Use at own risk! The gasses from the MRE Heating Pack is very flammable, so I strongly suggest keeping it away from a open flame..
Also, Check with you town law to see if it is legal!
Step 1: Things you need
1-2 MRE Heating packs (use more or less for size of bottle i suggest one or two for a 18-24oz. bottle)
Plastic Bottle with screw on Lid
An some water.. (OH NO NOT WATTER!)
Step 2: First
Step 3: Secent
You rip the Heating stuff into long thin strips. an well you put it in the bottle.. (MY GOWD... ITS SO HARD!)