WaterColorBot Paper
The WaterColorBot is designed to fit 9x12” watercolor paper (one of the most common sizes), and to paint up to within 1/2” of the edges.
Overall paper size: 9x12” (22.8 cm x 30.5 cm)
Margin width: 1/2” (12.7 mm)
Painting area (inside margins): 8x11” (20.3 cm x 27.9 cm)
For US Letter and A4 paper sizes— both a little smaller than 9x12” —align the paper to the top, and center it, using the marks provided on the spoilboard.
- You can use smaller-yet paper (e.g., notecards) on the WaterColorBot, even if they don’t fill up the spoilboard. The best ways to do so are to either affix it to a larger sheet of paper (9x12”, US letter or A4) with masking tape, or to clip it above larger paper on the spoilboard.
- Other types of paper not intended for watercolor often work quite well. We’re particularly fond of painting on “bristol board” drawing paper.
- Paper tends to warp as it gets wet, particularly with uneven wetting and lower grades of paper. Methods of dealing with this include pre-wetting and stretching paper, as well as holding paper down with tape or in blocks. Watercolor painting is an old art, and people have been solving these problems for hundreds of years; read up on the subject online or in books.
 Other media
Color Diffusing Paper, "a fabric-like paper with great texture" -- might be interesting to try.