Orthodontic spacer and floss set-ups are organized on a set-up holder which is a thin square or rectangular piece of plastic that has a plurality of complementary notches formed across opposite sides. The spacer is positioned more or less in between the notches on the set-up holder and one length of floss is disposed in one notch while the other length of floss is disposed in the complementary notch on the opposite side of the holder. In a supply of two or more spacer set-ups, the set-ups are separated from each other in this manner so that a particular one does not have to be untangled from a jumble of other set-ups. Kits provide pre-made set-ups already organized on a piece of notched plastic.