It initially seems like magic: the cochlear implant, which has already helped hundreds of thousands of people worldwide regain their hearing, can change its shape. The ingenious twist: 4D printing. For this variant, in addition to the now-familiar 3D printing, a fourth level is subsequently added, namely the factor of time. This innovation is designed to make hearing aids more comfortable. Every person’s ear is different, and getting the implant to fit perfectly is often an almost insurmountable challenge. The solution is a customized implant thanks to 4D printing. On the computer the implant is fed with the exact measurements of the ear in question and later 3D-printed—so far, so good. For the 4D printing, however, additional smart memory metals are used that can “remember” the original data input into the computer. If force is applied, the implant deforms and can easily be inserted into the ear canal. If the implant is warmed, it recalls its previous shape despite the deformation, returns to its original form and then adapts to a perfect fit—no magic required.