The blenders I use are the tortillon, stump, typing paper, tissue, chamois and felt, as well as a fan brush and sometimes a small paintbrush. As long as the material youre using doesnt stain the paper, you can use virtually anything to blend with.
Clothlike material can be wrapped around your finger or folded to obtain a clean corner. You can also roll material and secure it with masking tape to create your own stump. Its best to always test new materials you plan to use as a blender to make sure they dont leave a stain. Try to avoid using your fingers because you can transfer oil from your skin to the paper. Graphite is attracted to oil, making your fingers a very unpredictable blender. (Once upon a time, graphite was even used to dust for fingerprints.)