Giant Plaster Easter (Dinosaur) Egg





Introduction: Giant Plaster Easter (Dinosaur) Egg

These will blow the mind of a child on Easter morning and is a fun afternoon project.  I made these for a video I shot.  We needed large eggs that I could put a hand inside and break out of, and these worked nicely.  But I also found that they were fun to make, great decorations and kids love them.  Thanks to Tom Cline for showing me his Giant Plaster Egg 12 years ago.
WARNING, this is easy to do, but tough to master.  It will take several attempts.  Be patient and do this in an area you don't mind getting dirty.  The eggs tend to explode when you are making them, (nothing dangerous, but messy) and you will get plaster everywhere.

Step 1: Materials

Plaster of Paris-one box.
Bag of 9" balloons-round (but really Egg Shaped) clear is best, or white  or yellow, easy to see through.
Empty bottles of water-1/2 liter.  Easy to crush.
Mixing cup, more than 1/2 liter.
Mixing stick
Exacto Knife or Razor Blade
Spray paint
Towels, drop cloth, (did I mention this is messy?)

Step 2: Mix Your Plaster

The mix should be a bit runny, like a thin milkshake, it should pour easily, like syrup.
This is important; too thin and the walls of the egg will be too thin, too thick and it won't spread around enough.  Too much water and it will take a very long time to harden.  All I can say is try and try again and know it won't work the first time.

In this picture I use a piece of 1/2" PVC pipe.  Not a good choice, next time I used a screwdriver to mix.  Try to remove most of the lumps.  I bet a paint mixer on a drill would work well.

Step 3: Pour the Mix Into the Plastic Water Bottle.

The reason for the water-bottle is to force as much mix as possible into the balloon. 
A funnel will not work to get the mix into the balloon, but it would work to get the mix into the plastic bottle. 
The bottle should be full or almost full of mix. 
Very messy work.
Rinse bottle off. 

Quickly go to next step as the plaster is hardening as we speak.

Step 4: Squeeze Bottle of Mix Into Balloon

Place the balloon lip over the opening of the bottle. 

Hold the balloon on the bottom. With the other hand squeeze the bottle like a tube of toothpaste and get out as much as possible into the balloon.  Careful, the balloon can tear at the neck and you would have to start over.

Carefully remove the balloon from the bottle.

Throw out the bottle, it can not be reused.

Quickly move on to the next step, plaster getting harder and harder.

Step 5: Blow Up Balloon

You may want to quickly rinse the balloon off, plaster does not taste good.  Blow up the balloon to the desired size.  You might try blowing the balloon up and letting the air out before you start step one, just to make sure it is stretchy and no holes.

Careful, the balloon could pop and you'll have plaster everywhere.  And you don't want to do it in the garage, where your wife put the baby car-seat, and that nice picture of our wedding  and some throw-pillows she was meaning to bring inside any day now..  Because if you get plaster on that stuff...well, I wouldn't want to be there.

After the balloon is blown up, tie it off and quickly go to the next step.  Plaster, drying, times a wasting.

Step 6: Rotate the Balloon

Rotate the balloon quickly at first to cover the inside.  Here is where having a translucent balloon will help see where the plaster is inside.  Get it completely covered and keep moving it.  Look for streaks and weak spots and move the plaster to that area.  Once completely covered, keep moving the balloon slower and slower to keep up with the ever slowing plaster. 
The more even the coat is inside the better.  You can carefully tap the balloon lightly with your finger to keep the plaster moving.  Feel where the plaster is the most and move that part to the top to slowly settle over each side.

As soon as the balloon feels a little bit hard.  STOP.  Set it on a pillow.  You can rotate it a few more times maybe a quarter turn every minute. 

Step 7: Let Set, Dry, Harden

Let it set a couple of hours.  This takes a bit longer to completely dry than other plaster projects since it is completely enclosed in the balloon.   The balloon can still burst at this point.

Step 8: Remove Balloon and Decorate

With an Exacto knife or razor blade, lightly run the blade on the balloon. Just enough to cut the balloon but not the egg.   It will break away with a rip.  After a couple of cuts you can remove the rest with fingers.

Step 9: Decorate

Sand down the tip where the nipple of the balloon made a non-egg like mark.
Give it some more time to dry without the balloon.
You are ready to decorate.
Let your imagination run wild here.  Spray paint works.  You might try a primer coat to make it smoother, less porous.  I want to try painting it, covering part with masking tape and painting a gain to get stripes.  In the pictures I just painted it Silver and Pink. 
I really like the metallic colors.  Gold has worked nicely.  And there is the nice imagery of the Golden Egg.  
I'd love some ideas on decorating, this is not my strong suit.
Check out the painter pyramid instructable I did



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    I finally go this right :D For anyone trying this here are the things I leanrt! Use medical P.O.P (plaster of Paris) not the art shop kind, it coats thicker and better.
    I used the measurement of 250g x 150ml and it worked like a bomb!
    I also used yellow balloons but found that the thinner the balloon the faster it set, so the thicker balloons are the way :D
    Thank you for this once again Obediah!

    Thank you so much for this :D I've had such a great deal of fun trying to make them! I just wanted to find out if someone perhaps has measurements for how much water by how much plaster? Also how long should I leave if for? :) Thank you!

    i have a problem....after the plaster dries and i try to remove the balloon, the minute i cut the balloon the whole thing collapses because the balloon squeezes on the plaster. Any suggestions?

    I believe that you might need to:
    A) wait longer so the plaster is harder
    B) Use a bit more plaster to make it stronger
    C) when i popped it, i just cut a tiny hole in the end opposite the air valve of the balloon. and the balloon just peeled off by itself, and i just had to remove the last bits.
    D) in making these, I was successful about 1 in three times, So failure is an option.
    it's a challenge to great the right mix of water vs plaster, and the right amount of plaster total to use. And nothing sucks more than to have put in all that work to see it crumble. I would love to see a picture of the final when you do it!

    When I was a little kid I asked my Dad about a large Easter Egg (a folding paper one)  "what kind of bird laid that egg?"  And he said an Ooh-Wow bird. X-)

    As for the candy egg...  I think they inject or funnel the melted chocolate inside, spin twist and clamp or tape it closed, roll it around to get a good coating inside, then roll it around on cool/cold water to help harden the chocolate, (there probably might be a coating inside prior to injection, but maybe it wouldn't matter) then blow it up more to separate it, then pop it around the egg.  ....I'd guess.   I hope that wouldn't make a mess. <:-/

    Perhaps a way to pump air into the balloon would be better, unless these are going to be for yourself ('cause you'd blow your own germs into it if you blew it up manually). :-p

    Ithharden. Good try it this afternoon. I wonder how fast the chocolate hardens?  Can I re-melt and re-harden it?  Would it be better just to get a giant plastic egg as a mold rather than a balloon?
    I also think it would be cool to make the giant egg with chocolate and fill it with smaller store bought easter eggs.  I wonder how to do that?

    You reminded me that 3 years ago when I did the plaster egg, I would set it in a sink of water rather than on a pillow to harden.

    Good point about the air pump VS my own air.

    IF you could get the chocolate in the balloon to work - I'm not sure it wouldn't be too fragile unless you got a lot of chocolate in there - then it shouldn't be too hard to take a hot knife, cut it in half, fill it, then reseal with the same hot knife.  You could even decorate it with colored chocolate from the candy making supply. 

    Geez, I'm talking myself into trying this now.  :)

    Here's where I ask the Instructables Community for input...Plater seems very porous when painting.  I would love to get a smooth glossy, almost glass like finish if I could.  Is there something to coat plaster with to help with painting?  I've tried primer, but that didn't seem to do much.

    You could try wax. If you can get a soft wax, such as surfboard or hockey wax (called sex wax), then you could make it glossy.

    Can you paint wax?