My IKEA faucet aerators needed to be cleaned and I could not get them open so I remixed two designs into a better one. Both designs were much too fragile so I strengthened them as much as possible given the tolerences of the aerator. That may make them not compatible with non-IKEA versions of this style of aerator.
The second part of the remix is the Recessed (Cache) Aerator Keys (Multiple Sizes) from thingiverse:
https://www.thingiverse.com/thing:3652967
In particular I used the M18.5_Tiny_Junior_Wing.stl in my remix. I found the orginal much too tall and extremely weak even when printed with a strong PLA that has good layer adhesion. I've included a version without the slot key which is specific to the IKEA aerator. As well as the 3mf version of the file which should allow easy remixing should you want to tweak this design for your specific faucet aerator.
The author remixed this model.