It would be more fair to answer that with what substrate can’t you print on.
Did you know that the football for the world cup was screen printed?
We reckon we sell an ink that will print on almost anything, what is your challenging substrate?
We get lots of people who print onto skateboards / snowboards. You have met Rachel on the blog who prints on glass. Baby mats, swimming caps, lolly sticks, candles, estate agent boards… The list is endless… The great thing about screen printing is how versatile it is.