I was playing with some Chang Shapecrete the other day and I started thinking about casting spheres. I thought of using balls- from pingpong to yoga- but they all seemed impractical in one way or another. Small balls would be hard to fill while larger ones wouldn't be stable enough to hold their shape when filled with concrete. The thought of a yoga ball filled with concrete got me thinking about flattend out spheres and that lead to casting concrete in balloons.

Step 1: Preparing the Balloons

I used two different styles of balloons- large round ones and smaller, skinny ones. I cut the bottom off of a two liter bottle to create a funnel. Before putting the balloons on the end of the funnel I blew them up a few times to stretch them out a bit.

Step 2: Mixing the Concrete

I mixed the Shapecrete to a normally pourable consistency. I poured some into the funnel but it wouldn't flow through the neck. I emptied it and added a bit more water to thin it a bit more. This time it flowed through the funnel just fine.

Step 3: Filling the Balloons

I put a balloon on the funnel and poured some concrete but it only filled so much. I pushed the open end over my face to create a seal and blew. The pressure forced more concrete into the balloon.When it seemed pretty full I removed the funnel and jiggled the balloon around to bring all the air bubbles to the neck of the balloon. I burped all the air out and tied off the balloon.

I tried it with a long skinny balloon also. This time it filled up and I decided to twist it into several sections. The first balloon was a bit too full and it popped, making a mess. I filled another with a little less cement and managed to twist it into three separate sections. I set all the balloons aside to harden for almost two days.

Step 4: The Results

When the cement balls were hard I removed the balloons. The results were pretty cool- I ended up with six mostly smooth, flattened balls. I sanded a couple of them to remove the belly button where the balloon was tied or twisted. The results were pretty cool.

So what do you do with these weird balls? Paint them to look like bloodshot eyes and leave pairs of them in weird places all over your town. Create uniform sized, compact loads for your trebuchet, catapult or other siege engine. Paint them in pastel colors and leave them in the bushes in church yards the night before easter to totally confuse the little Sunday schoolers. Make over-sized game tokens for giant versions of board games (like backyardgammon or deckcheckers). Make colorful doorstops for everyone you know, repeatedly, until people either beg you to stop or you become a local eccentric/minor celebrity (OMG look! It's doorstop Donna! Is she buying balloons?!). Make cutesy paperweights for everyone in the office this year for Christmas even though no one actually uses paper anymore. Also get lots of pictures of your cat and wear lumpy sweaters every day of the year because you're that lady. Paint them bright colors, tie strings to them and give them to gullible children as anti-helium balloons.

I don't know- figure out what to do with your own weird balls.