Image from Dick Blick site
I was surprised to find out that plaster cloth was used to make these art pieces. I actually have plaster cloth purchased from Dick Blick hidden away in one of my cabinets. I'm definitely going to try this technique, especially since the warmer weather offers a bounty of flowers, leaves and interesting weeds.
To find other projects on the Dick Blick site, click the link near the top of the page that is labeled, For Artists - then click on Project Ideas.