I liked the idea of a socket converter, but the models available online did not fit the Polish standard socket properly. Because of this, I designed my own version.

This design ensures a tighter and more reliable fit compared to typical off-the-shelf adapters. Thanks to the improved contact, it is suitable for higher power devices.

I also created additional variants that work with phone chargers and other devices that do not require grounding.

Assembly requires two brass pins, which can be salvaged from a donor socket and soldered into place.
Once all is soldered, just put on the adapter and fill the gaps with a glue gun or epoxy. 

You can modify or adapt the design here:
https://www.tinkercad.com/things/hmfjLuYjfu1