Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:5819910.

This is a cap for the Z Axis to plug in a aluminium plate or a sensor.

Here are an example plug that i used: https://de.aliexpress.com/item/4000097123821.html

DC-Hohlstecker-Buchse 5,5 x 2,5 mm/zweipoliger Terminal-Block

It should be a tight fit but a lottle bit glue helps.