No skill required (Image: Gavin Kingcome/Getty)

MAKING a balloon in the shape of a bunny normally involves a rubber tube, a bit of deft twisting and a high tolerance for squeakiness. Now 3D printing means you can create any balloon shape you please.

But wait, you can’t just turn a digital 3D model into an uninflated balloon and expect it to look right when blown up – inflating the balloon deforms the initial shape.

So a team at the Swiss Federal Institute of Technology and Disney Research, both in Zurich, have taken desired 3D shapes and calculated what empty balloon shape should be needed to produce the inflated-balloon design. The system models the way a rubber balloon stretches as it inflates, then inverts this model to find the deflated shape that will most closely resemble the balloon when blown up. Some shapes are easier to replicate than others – flat regions or sharp edges pose particular difficulties, as air pressure tends to, well, balloon them outwards.

Having calculated the best uninflated shape, the team used a 3D printer to create a mould to make the uninflated balloon. They successfully tested the process on balloons in shapes including a rabbit, an elephant and Mickey Mouse’s head. The team will present their work at the Eurographics meeting in Cagliari, Italy, next month.