I just get almost physically ill when I hear of this kind of stuff. I can't imagine what kind of sub human would do this to a 7 week old kitten..makes you wonder if they'd do it to an infant as well.
We, too, have a continuing series of cats appearing, to whom we extend food, water, and shelter.
I will volunteer the use of the shop and a large inventory of hand and power tools for the re-education of the perp.
My personal choice is my battery charger and a soothing footbath of brick and tile cleaner for conductivity.