How to Make a Portable Thermal Cooler

How to Make a Portable Thermal Cooler


You can build a thermal cooler and save some money by gathering some basic material and following a few, easy steps.  It is an excellent option to use for keeping items cool in your backpack, campsite or bug out location, and you can easily customize this project based on your needs and preferences. 

Required Items

2 thermal food or shopping bags

1 Mylar rescue blanket

A couple of cold packs

Some duct tape


Remember that you can make your coolers as big or as small as you like, and there are no hard and fast rules with what types of cold packs to use.  However, you may want to consider using the ones that you can mold into different shapes so that you can tailor it to the design of your cooler. 

Preparing the Inner and Outer Lining


The first step is to cut off the top seal of the shopping bag.  This is usually a plastic handle attached to some type of zipper lock.  Cut just below the zipper line and discard the top piece.  The next step is to cut a vertical line down the middle so that you end up with two pieces that are equal in size.   Peel a few strips of duct tape and seal the cut side of one of the bags so that only the top remains open.  Make sure that the tape reaches all the way to the bottom so it creates a fully-insulated pouch.


The next step is to place the pouch you just created inside the other one.  Tape the exposed side of the outer pouch with duct tape as well.  You should now have a double-layered pouch with only the top remaining open.   Next, you need to tape the vent holes that are situated along the inner-wall of the interior pouch.  This will minimize the movement of air and increase the insulating capability of your cooler.  Make sure that each hole is covered, and try to position the tape in a manner that will not encroach on the interior space of the bag where your food or drinks will be stored later on.


All you need to do now is insert some ice packs, place the items that you want to keep cool, fold over the top and tape it shut.  You can also follow a similar process in order to create a single layered bag.  The difference is that the single layer will provide a few hours of insulation whereas the double can last for a day or more.




The purpose of the Mylar bag is to simply cocoon your cooler and provide an additional layer of insulation.  All you need to do is unfold the blanket and re-fold it so that it will fit around your cooler.  Normally, you just need to fold it in half along the vertical axis and fold it in half again along the horizontal axis.  Place your cooler in the middle and wrap.  Of course, you can modify this however you like, including making a pouch that is a couple of layers thick that you can place the cooler into as well. 

In any case, this simple trick creates a lightweight, non-bulky and customized way to keep items cooler for longer when you are out in the field.  Try this for yourself, and see how a little cold pack and the right insulation can give you a better cooler than you can find in stores, for a fraction of the cost.

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