We don’t think of computers as something you’d find in the 17th century. But [Levi McClain] found plans for one in a book — books, actually — by [Athanasius Kirker] about music. The arca musarithmica, a machine to allow people with no experience to compose church music, might not fit our usual definition of a computer, but as [Levi] points out in the video below, there are a number of similarities to mechanical computers like slide rules.
Apparently, there are a few of these left in the world, but as you’d expect, they are quite rare. So [Levi] decided to take the plans from the book along with some information available publicly and build his own.