This is a 2-position adjustable post sight for Nerf Elite-type rails. I'd tried a simple fixed sight before but it was no use for targets at different ranges. With this I set it up for 5m and 10m and just flick between them as needed.

The posts are independently adjustable via flat screwdriver, the posts also hold the key in position and limit rotation to 90degrees - make sure you check the key orientation before screwing-in the posts, otherwise the tab on the end of the key might end up in the way.

The rotating key and two posts should be printed at your highest-resolution as they contain threads. The posts were a tight fit but hold nice and snug, the body is just a friction-fit on the rails too but seems to work pretty well. See screenshot for suggested print orientation of the fine parts; this was done to reduce the chance of the key splitting along a layer line when adjusting the posts.

Creality

Ender 3

Yes

Yes

0.12(posts and key)/0.28(body)

20%-Adaptive

This printed at 0.12mm/layer for the key and posts, and 0.28mm/layer for the body. Bed temperature 60c, nozzle 205c for the budget PLA I'm using.