My mono prints are made using a gelli plate.  
Acryic paint and other mediums are rolled or painted onto the gelli plate.
Paper is placed onto the wet paint and then rubbed with your hand or a brayer.  The print is then pulled off the plate.  Often multiple layers are printed, one on top of the other.  Opaque and transparent colors are used to get the effect wanted for the final print.  Each print is unique and considered an original.