To what extent is it valid to fortify a home by reciting "Nun and [by] the pen and what they inscribe" (Quran 68:1) in its corners, then reciting Ayat al-Kursi while pointing with a finger to parts of the house, or circling it during the recitation and pointing? And what is the correct way to fortify a home if this is incorrect?

We have not come across the validity of this method. However, one can recite what is easy from the Quran and ask Allah through it, based on the hadith: "Recite the Quran and ask Allah through it." Among the established protective measures are reciting Surah Al-Baqarah, Ayat Al-Kursi, and the last two verses of Surah Al-Baqarah. It is mentioned in the hadith that Satan flees from a house in which Surah Al-Baqarah is recited, and that whoever recites Ayat Al-Kursi will not be approached by Satan until morning, and that whoever recites the last two verses of Surah Al-Baqarah at night, they will suffice him. And these two verses are not recited in a house for three nights but that Satan approaches it. Another protective measure is remembering Allah upon entering the house and before eating; for if a man remembers Allah upon entering his house and before eating, Satan says: "You have no place to stay nor dinner."