Probably not the best way but its the only option I have available atm that isn't a hassle. I've done it for about a year with success. Normally I make 30ml bottles in the plastic bottles. I make sure the lid is tight and drop 1-3 bottles into a sock. Tie a knot in the sock all the way down where its tight. This keeps the lids from unscrewing and coming off. Throw into dryer with dry towels or clothes. After 60 min steep is finished. Depending on how much it needs to be steeped I do may 1-4 cycles. So far I have done this close to 50 times with no leakage or incident. For extra precaution you could put bottles in a ziplock then drop into sock. I haven't done that or felt the need to. This is of course until I can get a ultrasonic cleaner.