what is the simplest Resonance machine. which can make indifferent level of resonance,

Allow me to be the first to answer your question.

Huh!?!

Resonance would depend on the system. What do you mean by 'resonance machine'?

What do you mean by "indifferent level of resonance"?

OK, let me take a guess and say that you're looking for a the simplest tunable-frequency resonant mechanism.

The simplest resonant mechanism is probably a tuning fork. You can adjust its resonant frequency by adding a slider-clamp where the tines meet, shortening the prongs that resonate.

But if you want to go tiny (which is one reason for looking for "simplest"), then you might consider a piezoelectric crystal, which resonates at a much higher frequency than any tuning fork, but is also much tinier. You can adjust its resonant frequency by a tiny amount by putting an electric bias across it which would change the dimensions of the crystal and change (slightly) its resonant frequency.

If you're just looking for something that you can use to illustrate variable resonance, I'd consider buying a metronome.

I don't know if this helps or not, but if you could clarify what you're looking for, I could probably provide a better answer.