I will not go into much detail explaining how these devices work, you’ll have to imagine how they work yourself (it should be pretty intuitive if you imagine the signal as a falling ball).
The “logic amplifier” is actually just copying value into another register. It’s called amplifier, because if this was to be built mechanically using falling balls, you would need to relieve mechanical stress caused by connecting all of the bits together.
I’ve also created a 4-bit multiplier gate, but I didn’t draw scheme for it yet. I’ll eventually post it when I draw it. And it’s also possible to make RAM, if you use I-gates instead of L-gates in a clever way.