Designed this to replace the spike in a solar light that kept bending. It screws in with a thread just like the original.

Printing:
It's in two parts that need to be glued together. This removes the need for support.

The scad file is parametric and you should be able to modify it to suit other manufacturers.

thread.scad contains a simple module for creating threads using a series of cylinders.

After a couple of attempts and tweaks the current version is happily in my garden. (Hence no picture.)

Printed on a Creativity CR-6 SE

Creality

CR-X

No

No

200

20

Apply glue and stick the two halves together.
After drying trim any rough edges on the thread.