I washed a batch of pre-cuts the other day but I put them in lingerie bags on perma press cycle then threw them into the dryer. I do the same with all my fabric. Even in the lingerie bags they will tangle so I separate them, then put them back into the bag and dry. I have also used old white pillow cases. I just tie them shut or pin them shut. sometimes, i'll lay them on a towel on the ironing board to dry then run the iron across in one fell swoop.