JÄRVFJÄLLET Headrest Extender

A headrest extension for the IKEA JÄRVFJÄLLET chair.

Fair warning, the bottom is so tight I had to dip it in boiling water to get it to fit.

I printed mine at 100% infill, for the durability and rigidity, and without supports; the undersides of the overhangs of the fancy top bit didn't look great, but those bits aren't visible when assembled, and the visible top surface was unaffected.