They are similar to the regular issue cards except for the white card stock.
The typical production process for a new deck starts with the choice between the most suitable material: card stock or plastic.
The board is a folded card stock which is laid flat for play.
Occasionally, one may find a domino set made of card stock like that for playing cards.
It was a large format publication, with color covers on card stock and black & white interiors.
The envelope held a note written on card stock.
More inexpensive models are made from heavy paper or card stock.
Scale models can be made from paper (normal or heavy) or card stock.
Someone had wrapped two pieces of card stock tied together with string.
Second, because the card stock is a little bit stiffer than paper, it's easier to shove them into the envelope.