This is a hollow range finder and stalk that is found on the side of many typical modern Mandalorian helmets, like Boba Fett from Star Wars. This design allows for a bolt to be placed as well as wires that are needed to supply power to the LEDs in the RF at the top
Print the version you require, there is a wire and a non wire version of the stalk.
The wire version comes in two halves,
For the wire version place a nut in the hole provided, and place wires in the channel before gluing the cover over the top.The wires should be long enough to thread through into the top part of the RF
Ideally the stalk should be printed in ABS or a stronger material, PLA may be too brittle.