The most basic element of origami is paper. There are many types of origami paper available in different grades, prices, colors, shapes, and sizes. Traditional origami papers such as washi and chiyogami are softer in texture than regular paper and are derived from plant fibers.
It can be overwhelming with all the choices to know what type of paper to use, however, in my experience simple is best (and most cost-effective!) Plain copy paper in different colors cut into square shapes works fine. I have found that kids in particular may want to draw or color on plain paper to create their own unique and personalized designs. However, It may be worth it to invest in origami paper in different prints and grades to accommodate any users who may express a desire to use traditional origami paper.
One suggestion I do have is to provide a variety of sizes to accommodate different levels of skills and abilities. In general, I like to start with larger sheets of paper with beginners and those with fine motor difficulties. You want to make sure that your user can feel confident and competent. In time, you may want to transition to smaller sizes as the user improves in skill and increases their mastery of folding.
This may not be an essential tool, however, it can be helpful in creating a variety of paper sizes if you do not have pre-cut sheets. Cutting paper to a variety of sizes for origami can be as simple as using a ruler to measure out dimensions and a pair of scissors to cut. However, this may not be precise. If precision is of importance, consider using a paper cutter either in guillotine or razor form.
Although the name implies bone, these folding tools come in a variety of materials including plastic, bamboo, and wood. Using this tool can be helpful for any clients who experience joint pain or have difficulty making solid creases with their fingers. If you do not have access to a bone folder, that is ok. I have found that a pocket ruler, metal spoon, or any hard flat plastic/wood/metal piece works well.
If you have a large amount of paper in various shapes and sizes, your materials can get torn, wrinkled, or messy fast if stored improperly. I like to store my small and medium sized papers in clear plastic bags to keep them neat, organized, and easy to see. For larger sheets, you may want to consider using a stackable tray or shelf system to keep them organized. I also like to use divided portfolios when I am on the go because you can organize paper into different sleeves and even possibly fit other tools such as bone folders, or pocket paper cutters.
There are many varieties of paper and tools to choose from to get started in practicing origami. In the use of origami as a therapeutic tool, I believe simple is best. Practicing origami should not be overwhelming or expensive. Use resources you already have and be creative!