How to Make a Wonder Box Cooker/Cooler




About: In a valiant attempt to keep myself from dying of boredom, I create.
A few years ago a friend showed up at a gathering with a frozen lemonade pie that had traveled quite a long distance and was still frozen solid.  “How?” was asked and the reply was “My Wonder Box”.  That was my first introduction to the Wonder Box Cooker/Cooler.  It was designed for the people in Africa who do not have enough fuel to cook their food.  Once a dish is hot, it can be moved to the Wonder Box and about 4 hours later, with no additional fuel expended, the meal is cooked.  It also works to keep cold things cold, and warm things warm.  Think how useful this would be if there was no electricity for an extended length of time.  Just use your BBQ grill to heat up the pot of food for 10 to 15 minutes and then stick it in the Wonder Box to finish the cooking.  The box holds the heat in to the pot using it to cook the food instead of the heat escaping into the air, and then having to use more energy to create more heat to cook the food. Here is how to make your own Wonder Box Cooker.

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Step 1:

Pattern for the Wonder Box (You will need heavy paper, a protractor (a paper one can be found here:, a pencil, a ruler, and paper scissors to make your own copy of the pattern from the one found here: ( this one is no longer there, try this one:
3.5 yards material (100% cotton)
Sewing machine
Sewing scissors
Fabric weights (pattern found here:
Straight pins
+/-12 gallons Polystyrene Pellets (bean bag filler, check the web)
Large piece of paper (to make a funnel not shown)
Empty 1 gallon ice cream bucket (not shown)

Step 2:

Print off the PDF that has the dimensions of the pattern pieces needed (there are only 2 pieces).  Using the ruler and the protractor, create a full size copy of each piece.  This took me longer than the cutting and sewing of the box.  Write “cut 4 pieces” on each pattern piece.  The small piece is the lid and the larger odd shaped piece is the body of the box.

Step 3:

Lay out your material, and layer it 4 layers thick.  This means you only have to cut once to cut our all four pieces.  Lay out the lid pattern piece on the material. Use the pattern weights to hold the pattern in place.  Cut out the pieces.

Step 4:

Repeat with the box body pattern part.

Step 5:

Set up the sewing machine.  Take two pieces of the lid and place them right sides of material together.  Pin one side together, from a point down a side and around to the point at the other end.  Repeat the process with the other two pieces. Sew each of the 2 pieces together with a ¼ inch seam.  Now take the two completed halves, open them up and pin them together point to point and then all the way around with a ¼ inch seam,

Step 6:

leaving a 6 inch gap in one side.  This is the place where you will turn the lid right side out and be able to put the polystyrene pellets into the lid.  Turn the lid inside out.

Step 7:

Repeat the process with the pieces for the body of the box.    The wide pointed end when all put together is the outside bottom of the box.  The narrower pointed end is the inside bottom of the box.  Again, leave a 6 inch gap in the bottom for the turning of the box right side out and the adding of the pellets.  Turn the box inside out.

Step 8:

 These are the Polystyrene Pellets, I bought from a friend. Her husband owns a business that has access to these wonderful little pellets. The bag I bought has enough to do 4.5 Wonder Boxes. One day my kids will each get one of these for Christmas.

Step 9:

This next part is a two person, outdoor, activity.  You need one person to hold the paper funnel into the opening in the lid.  The other person scoops the pellets into the fabric lid.  You don’t want to stuff it full.  You need it to be flexible to fit about different shaped objects.  It will take 4 or 5 gallon ice cream buckets of pellets.

Step 10:

Repeat with the body of the box. It will take 6 or 7 gallon ice cream buckets full of pellets.  Use straight pins to pin the openings closed.

Step 11:

Return to the sewing machine. Tuck in the edges of the opening and sew the open seams closed.

Step 12:

Take a moment tuck the inside end of the box into the center of the box.  This is the area that the pots, etc. will fit into the center of the box.  So you put the object you want to keep hot or warm or cold in the center and cover it with the lid.  This thing really works.

Step 13:

This is how to use your Wonder Box Cooker/Cooler. First fill a pot (that doesn't have a long handle) almost full with what you want to cook and enough water to cover it.   Bring the pot (with it's lid on)  to a boil and let it boil for 10-15 minutes.  Do not remove the lid, you will loose too much heat. 

Step 14:

With hot pads transfer the pot to the Wonder box and fluff up the sides so that they come in contact with all the side of the pot. 

Step 15:

Place the Wonder Box lid on top of the pot.  And let it set undisturbed for 2-4 hours. 

Step 16:

I opened this box after 2 hours and the potatoes were done. Can you see how useful this would be if you are in situation where there is no electricity.

Step 17:

So, this is the Wonder Box Cooker/Cooler. I use it a lot in my everyday life, so that when the emergency situation does come, and it will, I will think of it and use it, to keep my family fed. Enjoy!
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    16 Discussions


    2 years ago

    Wow lovely,would love one, gas is so expensive ,when your jobless,This would be a dream come true.


    4 years ago on Introduction

    Thanks so much for these instructions! I am going to make several of these because I can see how they will be useful for so many things. I live 30 miles from the grocery store and I am going to put a wonderbox in my car for bringing home frozen stuff. I can also see how it will save on electricity for anything that requires long, slow cooking and you can put your pot of beans or stew or whatever in and forget it for hours without fear of boiling dry or burning. What a great idea!

    My pots always leak a little. I know the box can be washed, but what a pain. Has anyone tried to use something like an emergency blanket (the thin metallic things) under the pot in case of leakage?


    5 years ago on Step 17

    Is it possible for you to post pattern for Wonderbox. It's no longer available on sites you linked. Thank you!

    1 reply

    5 years ago on Step 4

    I checked the sites you mentioned- but pattern is no longer posted.


    6 years ago on Introduction

    A great Instructable for the home use or travel or in a permenant camp situation. I have seen much plainer and rougher versions made with tea chests etc; but this one has the nice homely appearance about it.


    6 years ago on Introduction

    The link you have for the pattern doesn't work anymore (March 2013), I found another one here:

    I'm planning on making these! And thank you for the link to the instructable for the pattern weights too!

    2 replies

    You are welcome. The link was there when I published this instructable, last November, so I am grateful. If you don't mind, I will put the new address on my instructable, Thanks you so much.

    I did use it in my Greek yogurt instructable: Yes it is great for yogurt. Thanks for looking.


    6 years ago on Introduction

    I can definately see where this would be useful in traveling or needing the stove space to make other items while something else is cooking. However, I fail to see how this would be useful with zero electricity since you must heat it up first.......unless one is doing that over an open flame, then maybe. Good project though! I'll probaby try it.

    1 reply

    As I said in the Introduction: "Just use your BBQ grill to heat up the pot of food for 10 to 15 minutes and then stick it in the Wonder Box to finish the cooking."   I have a brother in New York State who has gone for several weeks at a time, during winter, without electricity and they use their outside BBQ grill to heat up food during those long time periods. It does work.  Thanks for your comment and for looking. 


    6 years ago on Introduction

    I used a bed + duvet once for this purpose for a Christmas dinner for which I lacked the proper amount of stove-pits. Worked like a charm ! You have to be creative when you have to feed 20 people with a 4 pits stove :)

    Love it! Just in time for holiday travel! And thanks for the 'ible on the pattern weights too! :)