Some people light Shabbos and Yom Tov candles by inserting a small wick into a “floater” then putting them in a glass with oil. Sometimes the hole in the “floater” where the wick should be placed is covered and must be pushed in to make the hole (usually done with the wick itself.) When preparing the candles on Yom Tov to light for the next day (Shabbos or 2nd day yom tov whatever it might be) is one allowed to insert the wicks thus pushing out the cover and “making” a hole/space to put the wick on Yom Tov?
It is not permitted to do this on Yom Tov, and one must make sure that the wicks are prepared before Yom Tov.
It is fairly clear from the general form of the wicks that the hole is not yet formed at the time of production, and pushing out the cover therefore “forms” the wick, which involves the prohibition of makeh be-patish.