Instructables
"Double, double toil and trouble; Fire burn, and caldron bubble." (- William Shakespeare, Macbeth).  Every Halloween display needs a cauldron, but they are hard to find...  When was the last time you saw a cauldron salesman going door to door?
 
So the only option is to make it!  Of course it has to be life- (I mean) death-size and bubbling with green goo!

This creation is a full-size cauldron with a removable clear 6-inch liquid-tight tray on top that can be filled with any liquid you desire and back-lighted any color from below.  The tray is plumbed with multiple air outlets that provide a constant stream of bubbles.  It sits on a glowing fire 'suspended' from its chain and tripod.

The cauldron consists of:

The Pot (Cauldron proper)
Liquid Tray
Support Base
Tripod
 
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Step 1: Paper Mache the Pot (Cauldron)

IMG_4787.jpg
Photo 1:  The cauldron is based on the shape of a large (~3ft dia) balloon picked up from a party supply store.  The balloon is paper mached with four or five layers of newsprint dipped in liquid starch.  Each layer is allowed to dry before applying the next.  After the paper mache ball is dry the top is cut off and the balloon is removed.

To give the cauldron support and allow space for the back-light and air pump a large plastic trashcan is cut down in height and placed inside the paper mache ball.  The height of the trashcan is selected to allow enough space from the top edge of the trashcan to the lip of the cauldron for the height of the Liquid Tray.  

Photo 2:  In order to provide inconspicuous access to the inside of the cauldron from the outside, a pass-through was provided in the bottom of the trashcan and cauldron.  This was done with slip-joint ABS plastic pipe with fittings that accept threaded plugs so that the trashcan could be partly filled with water in case in the future I ever wanted to use water and dry ice in it.  (Only a slight amount of water to keep the weight down.)

It is intended that the weight of the cauldron will be supported by the base that it sits on.  The cauldron bail / handle is only intended to steady it and complete the appearance.  Securement of the bail is provided by two threaded eyebolts slipped over two u-bolts that pass into the side of  the cauldron.  The u-bolts are tied to the trashcan by 12  gauge sheet metal brackets (framing ties) that are bent to shape and bolted to the trashcan.  This ties the bail firmly to the trashcan but not in a way that could support the weight of the cauldron with liquid in it.  The base does that.
Did you have any trouble with the liquid flowing back into the pump and clogging it?
wannabemadsci (author)  RoddyMacLean1 year ago
No problems with back flow as the holes in the liquid tray are fairly small and the air pump has a substantial output; made for larger aquariums. However, if you are concerned it is easy to put in an air check valve and prevent any problems.

Thanks for the question.
wannabemadsci (author) 1 year ago
Thanks everyone for the nice compliments!
poofrabbit1 year ago
Congratulations on being a finalist in the Halloween contest!!! Can’t wait to see if you win! Good luck!
Very smart! Love this - totally want to create something similar this year, Thanks for the inspiration!! :)
Wow your really talented, It's impressive to see all your work come to life in your pictures. I enjoyed reading how you made this.
chefsea2 years ago
Oh like this. I wish I had the patience to undertake this project.
powerman6662 years ago
What an amazing illusion! It looks so real!
Irdrive2 years ago
So cool I wish I thought of that!
this was an excellent instructable!
Oimi2 years ago
Hello there, this is a great unstructable!

Could you please answer a couple of questions:

How do you smooth layers of toilet paper papier mache?

How do you make your newspaper papier mache so smooth?

Thank you.
wannabemadsci (author)  Oimi2 years ago
Thanks for the question.

Only newspaper was used to make the shape of the cauldron. If you take a single sheet of newspaper, cut it into strips and dip them in liquid starch (the type used in the laundry for making washed shirts crisp; i.e. starched). when they are pretty saturated with the liquid starch they smooth down quite well.

When I pull a strip out of the liquid starch I 'squeegee' it through my fingers to remove excess liquid then place it and smooth it down. I have had very good results. There is a optimum time to let the newspaper sit in the starch, too short and ti will not stick or smooth well, too long and it falls apart too easily. Some trial and error works well here.

You have to be sure not to use too wide of strips as the curvature of the balloon will cause 'puckers' on the sides of the strip since is will not lay flat.

Good Luck!

l8nite2 years ago
adding to favorites, this could be really cool if we do another witch scene next year.. Great "ible"
Awesome! Great Halloween decoration!
wannabemadsci (author)  Penolopy Bulnick2 years ago
Thanks! It was fun to make.