These sketches were created in a free program called Alchemy, which is:

…an open drawing project aimed at exploring how we can sketch, draw, and create on computers in new ways. Alchemy isn’t software for creating finished artwork, but rather a sketching environment that focuses on the absolute initial stage of the creation process. Experimental in nature, Alchemy lets you brainstorm visually to explore an expanded range of ideas and possibilities in a serendipitous way.

The program is great for coming up with sketches and ideas very quickly, in the gallery below, I’ve assembled some of the quick work I’ve done with it.