That shallow pan of purple gel is called a hectograph. Yes, it is just a tray of gelatin and guaranteed purple fingers.

One typed using special "carbon paper" (actually covered with soluble ink) and pressed the paper the ink was transferred to onto the gelatin to transfer the ink. Then you pressed sheets of paper one by one onto the gelatin. And each copy got fainter and fainter...

It is essentially the same process as a spirit duplicator except that the "carbon" faced the back of the paper you typed or wrote on. Then you wrapped that paper around a drum with an absorbant layer that was saturated with alcohol.

By the time I got to grammar school it was all spirit duplicators. My mother remembers hectographs. Hectograps were commonly used for samizdat publication in the USSR as the government controlled other duplicators. You can't easily stop Jello.