Most use decal paper.Just make sure you buy the right paper.Inkjet decal
paper has to be sprayed with a clear coat.Or,Tiger use to sell the mug and
baseball cap printing system.You need a heat transfer machine for this type
of work
I use a color laser for my decals.You do have to keep in mind there is no
white ink or toner.Thus if you are printing a photo with white,you will need
decal paper with a white back.I keep both clear and white on hand.You can
also get a dye sub printer,such as a Primera..