Thanks for the comment.
Well basically, I'm trying to achieve something similar to this mechanism:
This is a telescope electronic focuser, since it has high gear ratios, you can't manually move it and I would like to have this option.
The way it will be connected is probably something like:
Motor D shaft>Coupler>Telescope shaft
Between that I'm trying to achieve this engage/disengage mechanism, I'm actually quite shocked that I can't find anything useful. I thought of quite a lot of ideas that could be possible, but can't find any metal part that I can use to achieve that, and once again, trying to avoid 3D parts.
Achieving that mechanism is not necessarily that hard, but finding something that's not gonna cost that much, is quite small, and doesn't create huge amounts of backlash is not easy to find.
If only I had a lathe mill, life would've been much easier, but I have to rely on either 3D printing or some actual metal parts I could find.
Hope that's clear enough.