Not a pretty piece of equipment.  I got a 10 amp varic of off e-bay for $30 and the plans from the web.  It is set up here for etching.  The one clip is attached to a piece of metal.  The blue wire goes into a block of wood which is soldered onto a metal plate that is on the bottom.  Over that is a piece of felt (brown) held down with electrical tape.  When using I set the varic at -0- put the blade on the metal plate. A stencil with my design on top of that. The  felt covered block is dipped in an electrolite solution, laided on  top of the stencil and the varic turned up.  I have been using about 10 on my dial.  I'm aware that this whole process can be dangerous. I have a healthy respect for electricity.
I also use this for Anodizing Titanium. The negitive clip  is attached to a scrap piece of titanium and placed in a jar making sure that it will not able to touch the positive clip that holds the useable titanium piece.  The color being determined by the amount of voltage.