Pin weaving: Combine yarn colors, textures, and fibers for eye-catching results. This would be a cool way to use thrums.
Create Intricate Fabric With Pin Weaving - Threads - excellent article on pin weaving with very clear instructions.
Make your own colorful and artistic fabric from yarn and leftover fabric pieces with pin weaving. The technique is surprisingly easy to master and produces lovely yardage for garments, accessories, and even framed art pieces.