Date: 18 Adar II 5578
From: Rabbi Moshe Sofer
To: Rabbi Falk
The responsum discusses whether an old Aron Kodesh (Holy Ark) can be used to make a coffin for a met mitzvah (unattended deceased), comparing it to the practice of using worn-out holy coverings for shrouds.
Source: Shu"t Chasam Sofer Collected §10