Paint or marker for insulated cup decoration I am looking to decorate one of those “Yeti” brand insulated coffee cups for my brother for Christmas, and I am not sure what to use so that the decoration does not wash off. I have researched a bit but have only found tips for porcelain mugs, and the surface of this cup is more like a lacquered enamel. I will tell him to hand wash but expect that he will want to occasionally use the dishwasher to clean it. Has anyone had any luck with decorating on this type of surface and having it hold up to a lot of touching and washing? If so, how did you do it? Thanks in advance!
You can fire artwork on porcelain and it will be permanent.  Pretty much any other surface won't be.  Even commercially applied artwork wears off and washes off eventually.
If you know the actual surface material/finish (like by contacting the manufacturer), you can optimize the decoration for adhesion and durability.
You can protect the decoration by building up a thick coating (via many light coatings) of a clear finish of some kind over the decoration.  A protective coating also makes optimizing the decoration material less important.  I'm not familiar with that particular cup but if the protected surface extends to the lip you drink from, the coating should be food-safe.
If the coating starts to wear off or gets scratched or chipped, you could reapply it or touch it up while the decoration is still intact.