A piece of hard cardboard
Dried leafs and flowers or material that will give a good relief
Aluminium foil (the heaviest you can find)
paint ( textile paint, block print paint)
Make a composition on the cardboard and attach it with glue.
Let dry COMPLETLY
Apply glue on the entire surface. Attach the foil to the composition. Make sure the composition is tightly encapsulated with the foil. Therefore press with your finger the foil in every surface. The back of the cardboard also needs to be covered with the foil.
Examine the proof and adjust as desired (more or less paint). After a few prints the press-plate will become better and better.