Hand-copying, of course, was how the manuscripts that make up the Bible made it through the centuries until the invention of the printing press. Modern people relearning ancient processes makes for fascinating reading.
In particular, all three bloggers mention that they didn’t stop to try to understand what they were copying because it would slow them down too much. That approach led to particular kinds of copying errors.
Each blogger also had specific letters that presented problems to him or her.
You can participate in the experiment if you know Greek fairly well.
You’d still get scribal errors even if you had people copy 2 Timothy in English—they’d just be a different kind of error. In many ways it’s astonishing how few variations are in the biblical manuscripts.