Marble adding machine

[cicatrix]

I just stumbled on a fascinating piece of woodwork that can actually add numbers.

I know the theory, of course, but seeing how it works is something different:

[lajoswinkler]

It's fun to watch, but it's not very helpful if in the end you again have to add the values to get the final result. Adding machine requires of user to add. Kind of useless, but fun nonetheless.

I've seen this guy's channel. He made an air raid siren using wood. Rather neat stuff he has there.

[EdFred]

I have a clock that is similar. It has a 1 RPM motor that drops a stainless steel ball at the top.