Q. Hello Rabbi. Can someone make Kiddush using a disposable plastic cup?
A. It is common in some synagogues that when a large Kiddush is offered, the late comers who are reciting their own Kiddush use the disposable plastic cups. Some prefer to use a double cup (one inserted in the other).
However, Horav Shlomo Miller’s Shlit’a opinion is that due to the honor involved in complying with this important mitzva, a proper metal Kiddush cup should be used. (Washing the existing one and reusing it).
If that is not practical due to the need of the many, the shul should provide silver colored plastic copies of a ‘becher’ available in stores.
Rabbi A. Bartfeld as revised by Horav Dovid Pam, Horav Aharon Miller and Horav Chanoch Ehrentreu Shlit’a.