The Australian made Popball was my favourite toy when I was a young kid. A simple rubber ‘half-ball’ style toy that uses its own stored kinetic energy to launch itself into the air.
These simple toys have been around for a long time and you can still buy them today. But the Popball I remember was far more powerful than the newer ones! And that led to it being banned across schools. Urban myth ran wild and there were stories of eye and face injuries. The black ones were banned first which didn’t concern me as I had a blue one. But shortly after, all the colours were banned. I kept my blue Popball all the way into my adulthood, but lost it somewhere along the way.
Now, 35 years later, I wondered if I could recreate the toy using materials and processes that I have on hand? So, I set about designing the toy in CAD and did the first obvious step: attempt to print it using TPU filament. Most TPU filaments have a Shore hardness considerably higher than a Popball (~55A), but I had some 90A TPU handy and printed my first Popball. Unsurprisingly, it didn’t ‘pop’.
The Original Popball was made by Peter Fish Toys and as part of my project research I managed to get in touch with Peter Fish who is now a semi-retired toy maker. He answered a lot of my questions and some of the information he passed on to me was fascinating. For instance, he black Popballs were banned first because recycled car tyres used in their manufacture made them too powerful (that one wasn’t an urban myth!). He wasn’t convinced that you could 3D print a Popball, but I was up for the challenge. I ordered a much softer TPU filament form Recreus and while I waited for that to arrive from Spain, I looked at some other methods to produce a Popball.
Local resin manufacturer Monocure3D had just released their first batch of Pro Rubber-like Resin. I snapped up a bottle and tried SLA printing a Popball. It took me a few prints to dial in the settings, but I produced a very nice looking Popball. But it did not pop. The Pro Rubber-like resin was flexible, but not elastic.
I have dabbled a bit in basic moulding, so I thought I may be able to make one from polyurethane rubber. I 3D printed a two-part mould from PLA filament and used Smooth-on’s 60A VytaFlex. The Popball came out looking very nice, but again there was no ‘pop’. Taking inspiration from recycled car tyres, I thought that adding carbon black (common additive in car tyres) may add some more stiffness to the polyurethane rubber. This approach worked, and I got my first functioning Popball. But adding the carbon black also weakened the Popball, so this wasn’t the right approach.
By this time, my Recreus Filaflex 60A Pro TPU filament had arrived. And this proved very difficult to print. My first prints failed and I jammed the extruder on my Bambulab X-1 Carbon. It was so soft that it even came with a disclaimer that Recreus is not liable if you can’t print it on your printer! It took a lot of trial and error, modifications to filament feeds and the extruder, but eventually, I got a print that I was reasonably happy with. And it popped! Better than all the previous ones I’d made, but it didn’t perform as well as an original Popball. But still, it was on par with the newer generic Popballs – and I was happy with that.
This project exposed me to some new materials and processes, but most importantly, it answered some questions that I’d had in my mind for over 35 years!