The hectograph or jellygraph was a predecessor to the ditto machine. It used Perkins mauve as a transfer ink
HECTOGRAPH FTW! Gelatin, transfer paper, big pan...make your own printing press. OK, it's closer to a mimeograph, but still. http://blog.lib.uiowa.edu/speccoll/2013/07/16/what-the-hectograph/
Edvard Munch, Self-portrait on Sofa, 1925. Hectograph on cardboard, 500 x 382 mm. Private collection© The Munch Museum/The Munch-Ellingsen Group/2013, ProLitteris, Zurich.
How to make a hectograph
Hectograph - Wikipedia, the free encyclopedia
We tested making hectograph prints with gelatin.
Who remembers the hectograph?
Making Copies with the Hectograph
I remember Mrs Hall in Year 1 using a hectograph to make copies of worksheets! They came out purple print. Some times she would let us peel them off.