Acrylic blocks have been around since before I started stamping in 1996. (Yep, I'm dating myself here!) They've always been useful as a temporary mount for rubber dies, and then with polymer stamps when those came onto the scene many years later.
However, it wasn't until fairly recently that we started seeing them being utilized as a "stamp" of sorts themselves. Somebody got the brilliant idea to ink up their acrylic block and put it to paper, with lovely results.
Michelle Pearson likes this technique because "it is very quick and easy and beautiful...I tapped the distress pads on my long acrylic block before spritzing with water and stamping on watercolor paper."
You can find a step-by-step tutorial here, which outlines the process she followed using 11069SC Soaring Eagle Clear Set to make this card:
11070SC Songbird Clear Set contains greater contrast:
The resulting bold splashes of color are really striking:
The stamps from both 11013SC Brushed Calligraphy #2 Clear Set and 11071SC Holy Spirit's Fruit Clear Set work great for this fun technique!
I think the "wet" watercolor look of the horizontal darker green stripes mimics the juicy pear theme here: