If you make fermented vegetables or conserve pickles, do not forget: the ingredients must always be underneath of the water!

How to achieve this against the veggies that always just want to get to the fresh air? Use my jar top press plate that ensures that all of those delicious veggies keeps themselves below water level!

Print it from PETG, and resize it to a bit wider then your jar's mouth. Bend a bit during insertion and the jar itself will keep it steadily in place. Your task is just to fill it then with the proper liquid above my jar press plate. 

Resize for your needs, but KEEP THE THICKNESS at 1mm, as that is sturdy enough but easy to bend!

The honeycomb pattern achieved by slicer parameters so do not be surprised that you do not see the properly the model in prepare mode just in the preview tab!