You shall not make a molten idol… (Leviticus 19:4)
Remember the story in the Midrash about young Avraham (Abraham)? His father, Terach, sold idols for a living. One day, Avraham was left alone to run the store. He drove away all the customers by shaming them for wanting to purchase something as ridiculous as an idol. Ultimately, he smashed all the idols but he left the largest one alone, putting the stick in its hands. When his father came back and freaked out, Avraham pointed to the sole surviving idol and said, “He did it!” Terach replied, “What are you talking about? It’s just a hunk of stone – it has no power!” This gave Avraham the last word: “Do you hear what you’re saying?” (See Bereishis Rabbah on parshas Lech L’cha.) No one suggests that Avraham shirked on his fiduciary responsibility to the family business, since he was answering to a higher call. Even if a person does not himself believe in idols, it is still prohibited for him to make them for others.
Our job is not merely to look out for ourselves. We have to look out for Number One but that means God, not us. If we facilitate others in idolatry, that affects the world by bringing more idolatry into it. We may not be able to eradicate such practices, but it’s certainly against our best interest as Jews to help them to thrive!
There are some differences in practical application if one makes an idol for himself or if he makes it for someone else. For example, if he made an image intended as an idol for an idolator, it is considered an idol with all that entails as soon as it is finished. If he made the image for a Jew, it is not considered an idol until it is worshipped. (“All that entails” can include whether or not the sculptor deserves the punishment of lashes, whether or not the image must be destroyed, whether or not the money paid for making it is permissible, etc.)
This mitzvah applies to both men and women in all times and places. It is discussed in the Talmud in tractate Avodah Zarah on pages 51b-52a. It is codified in the Shulchan Aruch in Yoreh De’ah 143. This prohibition is #3 of the 365 negative mitzvos in the Rambam’s Sefer HaMitzvos and #10 of the 194 negative mitzvos that can be fulfilled today as listed in the Sefer HaMitzvos HaKatzar of the Chofetz Chaim.