@pimoore There is definitely a much wider choice of paper quality, thickness, coating, and other varieties in the notebook space than in the traditional index card one. Most index cards are on the rougher/pulpy side (Oxford, Amazon Basics, Staples, etc.), but I've not run into many that felt like plastic, aside from Rocketbook's cards which are a bit more durable for being erasable/cleanable and reusable. For those into some higher end/luxe super smooth cards, perhaps Exacompta's Bristol cards are worthwhile? Of course, if one isn't as particular about their usual index card thickness, one could easily use off-the-shelf paper or custom cut their favorite paper and have thinner "slips", though with heavy use over time (thumbing through them), these can show significant signs of wear.