Having come across a small Chinese ball within a ball, I wondered how it was done? Carving was my guess and so I purchased a block of wood to give it a go but knowing my woodworking limitations this project quickly morphed into making a giant dice. Then another idea stuck me, 'If I can't make it - working from the outside working inwards, how about starting from the inside and working outwards?' Here how I went about it....

Supplies

Air drying clay

2 balloons

PVA glue

Aluminum foil

Step 1: Make an Aluminum Ball

The very inner small ball was made by scrunching up some aluminum foil. Gentle taping with a hammer helped to get the ball hard and round. The ball was made about an inch in diameter.

Step 2: Rolled Out Modelling Clay

This small aluminum ball was pushed into the mouth of a balloon. Being small this was easy enough to do. Next, the balloon was inflated to be about 3 inches in diameter and tied off.

Some air-drying clay was rolled out and used to cover the balloon. An old toothbrush and water helped to join the seams together. The balloon ball was left to dry.

Step 3: Holes

When the ball was almost fully dry12 circles were made into the clay ball using the end of a pipe. A circle cutter could have also been used but I had the pipe handy.

Slightly deflate the ballon because when the clay fully dries it will shrink a bit. Do this by placing a piece of tape on the balloon, prick it with a pin, allow to deflate slightly and then reseal with additional tape.

Allow the clay ball to fully dry.

Step 4: Sand

Once fully dry sand the ball and prick the inner balloon allowing it to fully deflate.

Step 5: Coat With PVA Glue

Coat the dried clay ball with PVA glue. This will prevent chipping and make it stronger. Remove the balloon from around the inner aluminum ball by cutting away with a small pair of scissors.

Step 6: Third Ball

Now the next bit is a bit tricky as we want to get another balloon around the outside of the clay ball. This was archived using a 900 ml empty beer can with a bike valve attached, insert the previously created ball into the can, stretch the mouth of a balloon around the beer can's mouth and inflate, allowing the clay ball to be slide into the inflated balloon. Carefully remove the inflated ballon from the mouth of the can and adjust the diameter of the outer balloon before sealing it.

Cover with more clay, once again sealing the edges using an old toothbrush and water and allow to dry.

Step 7: Cut Some Holes

Cut out some more holes on the outside of the almost fully dried clay ball. I used a circle cutter this time and cut out 12 holes, being carefully not to damage the inner clay ball.