Lay out your plastic human skeleton on a table. Build up the muscles on the skeleton using modeling clay, foam or expanding insulation. Use an anatomy book as a reference for where muscles go and what direction and textures they have. Allow these to materials to dry and/or set up.
Mix corn syrup, red food dye and polyurethane together. This will be the fake blood you will be painting on the muscles you created. Allow this mixture to glob and pool in strategic locations to make the corpse look “gooey.”
Create exposed intestines using opaque white pantyhose legs stuffed with plain gelatin. Create crimps and crinkles in the intestines by tying fishing line loosely around various spots. Coil the fake intestines and fit them into the abdomen of your corpse.
Dress your corpse in tattered clothing. Splatter the clothing with your blood mixture. Rub the clothing with dirt to create a decomposed look.
Use black lacquer to darken the eye sockets of your corpse and darken the inside of the mouth of your corpse.