LEGO Puzzle Box - version 2 

Thanks! There's an axle connector inside that's connected to another axle with a small gear on it. When you allow access to the hole by pushing the green button, the axle slides right into the axle connector.

@@Nattokusai So when you put the axle in the hole sometimes you have to spin it a bit to make it thread properly?

Just a little, but it doesn't require a lot of effort!

@@Nattokusai Nice. I built a model of how the general design works to test it, works pretty good. I have discovered something, though. The axle can mimic a very small gear, so if you had a small dark grey gear threading with the axle on a rack and pinion setup, then you could slide the axle in smoothly, but turning it may be a problem.

I used a free app called YouCut to make the video. The music was in the app. I think it's called "Lofi Study".

Sorry, no tutorials yet. I can show you what it looks like on the inside.

@@Nattokusai that’s ok