The Japanese government announced on April 1 2019 that "Reiwa" will be the name of Japan's new era to start on May 1 2019. A service that can create and publish the "new era" arbitrarily is on 新元号ジェネレータ.
The thing here is a 3D-printable version of "new ear generator". The board is changeable so you may just print an announcer if you don't change the corresponding thickness. You may, of course, use a paper note, too.
The announcer.stl has the default thickness. You may print it and only generate the board on Thingiverse Customizer.
If the preview isn't shown on Thingiverse Customizer, download the .scad file and use OpenSCAD directly.