A cardboard box, with three rows of brass type matrices. Each piece can produce one letter or one character, in a specific typeface, in one size. Each matrix is a slice of metal about an inch wide, an inch & a half tall, and just thick enough for the character.
Sorting of two boxes full of matrices, from one type face, completed. I sorted into wooden racks. The left rack holds all the capital letters; the right holds the lower-case letters plus numbers, punctuation, and some decorative pieces. "Lower case" is actually a printing term. Capital letters were kept in an upper rack or case; what we call lower case were stored in a lower rack.
A Linotype machine, invented by Mergenthaler. The operator touches keys and the matrices for the letters, spaces, punctuation and other characters drop down into a line. Then the machine casts the type, and then the matrices move back up to the top of the machine and get automatically sorted back into place. Amazing. Then the type gets put together, line by line, put in a page frame, and then it goes off to the printing press.
I found a secret message in the order of the matrices I was sorting. Mostly there were batches of capital Ws, for example, with some random items mixed in. Suddenly, a batch read "DUES PAID."
Spent the day at the C. C. Stern Type Foundry, sorting & inventorying type matrices. They have Monotype & Linotype, so can cast type one character at a time, or a line at a time. Brilliant technology.