After making all the ball puzzles, we realised that we needed an interesting way to sort them in such a way as to give a combination for a lock. The original idea of using buoyancy failed, so I quickly came up with this prop taking heavy inspiration from carnival clown games.

The mechanism for this was pretty straight forward, as I was just going to use gravity to separate the balls using size. To mix the order up a little and make it less predictable I used a shoot to move the order of one of the balls.

I 3D printed and epoxied all the parts together and made sure to give it all a good test. I just used PVC pipe as the exit shoots under my mechanism, and the addition of two wire runners to add a little more initial acceleration to the larger ball.

I then made a nice little plywood box to house the mechanism.

The next step was making the clown head with the open mouth for feeding in the balls. I found a sufficiently creepy 3D model for free on thingyverse, and set about changing it, I did this by designing the ball path in solids and subtracting it from the model. then tweaking everything in mesh mixer to look the part. I also used the addition of a solid hat, which I then also tweaked in mesh mixer.

I printed the clown head in two parts, I used a hole saw to put corresponding holes through the two joining surfaces so that the internal cavities were connected. I also filled any small openings or cracks with filler, then mixed up some ordinary polyester fiberglass resin and sloshed it around inside until it set. This made the two halves incredibly strong, I then epoxied them together and filled them with rapid expanding foam.

I then gave everything a lick of paint and attached the head to the ball sorting box. I made a little poly-carbonate panel for the sorting bay and the rest is history.