I thought it was high time I had a thorough and dedicated examination/experimentation of textures, colours, and composition, so I grabbed a small sketchbook and quickly filled it with hurried brush strokes in bright and watery acrylic alternately, as well as lots of bits and pieces stuck in with glue - old scrap paper, cardboard, and photos. This formed a textural layer to have a good scribble over (or to paint over a second time or stick things over).
It's amazing the effect changing (or attacking!) your "canvas" can have on the form and pace of your creations and your motivation to make them. The psychology of a daunting white page has been well remarked upon, and since many of my projects require construction of a base layout as a first step, it's a useful (and really enjoyable) practice to experiment with base colours, textures, lines, and other formalistic elements in a project specifically designed for such experimentation.
So in light of that, here's my sketchbook focused on painted textures, shapes, and general formalistic play - a basic creative joy in its own right and a useful learning tool/test exercise.