This is a replacement vent lid for Pyrex containers like this one:

https://www.pyrexware.com/pro-3-qt-round-vented-plastic-lid-turquoise/1121732.html#start=33

This is just for the vent cover in the center of the lid.

DISCLAIMER: Depending on what material is used to print it, it may or may not be food safe or microwave safe.

I printed this using ABS plastic so that it was flexible.

This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/dBpGuZqLRg3