These disposable applicators (lifted directly from the dentistry business) let you apply tiny amounts of oil, paint, glue, stain, etc., very accurately and controllably.
They are equally good for cleaning hard-to-reach areas. They have articulating necks that let you set them to reach around corners. The ball-head styles (approximately 3/64", 5/64", and 7/64" diameter) have lint-free, non-absorbent fibers that have quite good fluid-holding and flow characteristics.
The 1/16" diameter brush head has 1/4" long bristles. All brush styles are about 4" long and are available in packs of 10 or as a set of 40, one pack of each style. We recommend you just buy the set of 40. You know you will use them