This is a strain relief/cable protector cap specifically designed for 4-pin pluggable terminal blocks (also called Euroblock) and a telephone cable (flat cable with 4 wires inside).

Creality

Ender 3

No

No

0.12

None

It may be a good idea to print at 0.12mm layer height and 50mm/sec for the most precise fit. It should have just enough friction on both the cable and the terminal.

No need for supports, rafts, brims, or infill whatsoever, just make sure to rotate it with the wide end down.