Foil printing is one of the most luxurious forms of letterpress printing. most people love the look of hot foil stamping, but can't figure out why it costs more than traditional letterpress printing. foil stamping requires custom copper dies + a printing press or machine that heats up, sometimes to temperatures as high as 400 degrees. the cost of the foil also exceeds that of ink. the results are amazing.
don't be fooled by Instagram filters -- the only way to achieve opaque white on colored or kraft paper is with white foil. there are other matte colors available, as well.