I say, and with God's help: The act itself is prohibited; due to the touching or revealing of private parts without necessity, it is not permissible by Sharia. Even if the artificial nail is made to last for days, it is another prohibition. Therefore, you should refrain from this act; for this world does not suffice for the Hereafter, and whoever leaves something for the sake of Allah, He will replace it with something better. And Allah knows best.