Any watercolour surfaces as watercolour paper substitutes?

At an arts & crafts store you should be able to buy a few large (like 32 x 40 inch) white mat boards. A mat board is that board used for picture framing. It's cut to make the rectangle outside the picture.

Mat boards have a textured surface, not smooth, which you want. This is maybe not the best surface for watercolor, but it will at least do for a student.

To get the most from a board, cut it down to small pieces you can make different paintings with.

With all watercolor paper - and with boards as well - you have to prepare it to keep it from warping from the paint. Rub the board front and back with a moist cloth, then attach it to a drawing board with push pins or masking tape. Wait till it's completely dry before you paint on it.

You might also find something to use at an office supply store like Staples, maybe even watercolor paper.

Chinese brush painting materials are cheap and very rewarding to paint. There’s a definite technique to it. The rice paper is very soft and requires delicate control along with the many types of brushes available.