Scented wool dryer balls

Tightly wound, felted wool balls that tumble in the dryer to soften and shorten drying, with a few drops of essential oil for scent.

Essential oils are flammable. Add the drops to dry balls and let them soak in for at least an hour before tumbling, and use low or medium heat. Never put freshly oiled balls in a hot dryer.
Clean the lint filter before every load.
Keep dryer balls away from dogs, which may chew them. Keep undiluted essential oils away from pets and children.
Test brightly dyed yarn by washing a scrap first. It can bleed onto light laundry.

Steps

Wrap yarn around two fingers about 10 times, slide it off and wrap across the middle to start a core. Keep wrapping tightly in different directions until the ball is about the size of a tennis ball, around 2.5–3 in (6–7.5 cm).
Tuck the loose end under several strands with a crochet hook.
Push the balls into the pantyhose one at a time, tying a knot or string between each so they can't felt together.
Wash on the hottest cycle with a load of towels, then dry on high. Repeat 1–2 more times until the strands have felted into a solid surface.
Cut the balls out of the stocking and trim any fuzz.
To scent: add 2–3 drops of essential oil to each dry ball, let it soak in for at least 1 hour, then toss 3–6 balls in with a load and dry on low or medium heat.
Re-scent every few loads. Replace or re-felt the balls when they start to unravel.

Balls unravel or won't felt: The yarn is superwash or acrylic, or it was wrapped too loosely. Use pure non-superwash wool, wrap tightly, and run extra hot cycles.
Oil stains on clothes: The oil didn't soak in. Wait at least an hour after adding it, and use fewer drops.
Faint scent: Heat drives off essential oils. Use low heat and re-scent more often, or use scent booster crystals in the wash.