To honor Rabbi Kanievsky, he and a friend were learning a halachic (Torah law) ruling written by Rabbi Kanievsky in which he stated that the stones for the Temple had to be cut by Jews with the intention of honoring God’s name.
“We have a mitzvah (Torah commandment) to build the Temple. This mitzvah is not conditional or time-bound. We have this requirement at all times. So it is a pity that we are not actively engaged in it. Right now, it is politically complicated for us to begin building on the Temple Mount but that does not exempt us from this mitzvah.”
Rabbi Lipo realized that it was possible to begin to actually perform this mitzvah by preparing the stones that will be used to build the Third Temple. He explained that Rabbi Moses ben Maimon, the medieval Torah authority known as Maimonides or by the acronym Rambam, taught that the stones for the Temple building were cut outside of the Temple Mount and transported to the Temple Mount. Once on the Temple Mount, it was forbidden to use iron tools to form the stones. It was, of course, forbidden to use iron tools at any stage to form the stones for the altar.