Electric fly-squatter

I have tested a cheap fly-squatter on my lover's cockhead. And thrilled of its effect.

Now I plan a session, where his genitals - especially his cockhead - are totally locked (and of course his hands kept away). I want to use it maybe 100 times and experiment with shorter or longer touches.

On Fetlife I found a lot of ideas on electric fly-squatters - many of them very technical. Now I want to do my own experiences! Poor, poor lover.