I'll show you how I made it. First I snagged a skull and crossbones off the Internet, mocked up the label and printed it in red on white paper. Then I got out my pastels.
To make it look old and yellowed I shaded it lightly all over with a yellow ochre color...
and rubbed it all in with my fingers.
Then I did that again with a sepia color, but a little lighter.
Next I took a rusty red and made irregular swirls around the edge....
and blended just those areas using a circular motion.
The last touch was black all around the edge and a few tears up and down from the edges.
I smudged those in straight lines. The only thing left to do is trim the edges. I didn't trim it straight; I faked a worn crooked line, but I suppose you could use deckle edge scissors. Then I glued it to the transformer. Looks old and creepy, doesn't it?
I also snagged some poison labels off the Internet, printed them out, aged them and glued them to old bottles. I added some bloody fingerprints too by wetting my fingers, patting them in red and brown watercolors and touching the bottles all over. Of course, the bottles only have colored water in them, but they look pretty scary, don't they?
These bottles and the Jacob's Ladder will be in the Living Room which will be set up like a mad scientist's laboratory. You know, strange potions, gruesome tools, skulls, bones, body parts in jars. Hmmmm, does anyone know where I can borrow a gurney?