This is an extremely fun printmaking process that you can do at home. You mix up a thick batch of gelatin and pour it into a flat pan. I used a piece of plexiglass with modeling clay around the edges to create a wall. You pour in the jello, scrape off the air bubbles, and let set. You can visit here for a more detailed tutorial on making the plates.
Then comes the fun part - printing! Using water-based inks (I used Akua inks for this experiment), you just roll the ink on with a rubber brayer and then place hand-cut paper shapes, plant matter, string, stencils, and anything fairly flat on top. Place your paper over the jello plate and gently rub, then lift it up. You can experiment with using negative and positive shapes by laying objects and stencils down, directly painting strokes of ink on the jello slab, and layering colors and textures.
This jello print was made in layers. i rolled up ink and placed plastic netting over it to create some texture, then printed it. Then I inked up an orange color and placed leaves on top. The result is shown here - the leaves acted as stencils by blocking the ink transfer, and remained as white shapes. The great part about using jello is that it has a bit of natural suction when you press your paper down on it, so that ink lifts up very easily. There is no need to apply a lot of pressure. You can re-use your jello slab, even if it gets moldy! Just rinse it a bit, blot out the excess moisture and make use of the interesting holes and cracks in the jello.