I saw a demo recently, the guy used a simple 1.75amp trickle charger for 12v battery, found at wally world auto section for 20 bucks.
Attach a stainless piece of barstock on negative lead, by attaching wire with screw. Used small piece of cheap felt found in walmart hobby section. Got the felt only slightly damp using mix of apple cider vinegar, water, salt, and a little dish detergent.
He "zapped" the stencil in one second bursts, maybe 10 times to 15 times. He said if you hold it to the stencil for long periods, you burn it up.
Get stencils made at Ernies or make your own if you are inclined.
It worked very well for him.
I am getting set up to do this.
But I'll keep my whack 'em stamp for when it is more appropriate.
Dan