This is a pencil he made from numerous scrap parts and a small amount of custom parts. He did it largely referring to the internal structure of the actual Automac E/E500, hence his one has all the main functions as well.
The Automac E style of auto lead advancing is slightly different from what we see on most auto MPs in general. For most auto MPs like Orenznero, when the lead is used up, the next stroke we write pushes the spring loaded lead sleeve inwards. Once we lift the pencil from the paper, the lead sleeve instantly extends back to full length, bringing the lead along. For Automac E/E500, the lead sleeve does not instantly extend back. Instead, it shortens as we write, until it reaches the end of its travel and extends back to full length completely. It’s very similar to how a base Orenz works, except the internal mechanism is doing that final one full click for you.
This mechanism is somewhat similar to security tags seen in clothing stores. The original E500 has 6 tiny steel balls inside, but he only put 2 inside his, for ease of assembly.
The auto lead replacement is less complicated, basically when the tip is pushed fully inside it pushes an internal part that opens the clutch, which allows the next piece of lead to fall into the clutch.
He even solved one problem of the original Automac E/E500, where when there’s around 2-3mm of lead left, the tiny final piece of lead is fit loosely enough to freely rotate within the lead sleeve, making it hard to keep the sharp side facing the paper (once you apply writing pressure, the lead will rotate until the flatter dull side faces down). His creation has its lead retainer going all the way to the tip of the lead sleeve, holding the lead securely until the final 0.5mm length, and by that time the lead bit is already ejected by the next piece of lead being loaded to the tip.
The original E500 uses a conventional rubber lead retainer ring, which only covers the rear end of the lead sleeve, hence the spontaneous lead spin when the lead completely loses contact with the rubber ring. However, if we simply made the inside of the lead sleeve as grippy as the rubber ring, that would be too much drag in normal lead advancing, which translates to too scratchy of a writing feel (the lead is not being fed enough, so the lead sleeve constantly scratches the paper).
His solution was to get rid of the rubber ring entirely, and used a thin plastic film “stripe” that went all the way through the inside of the lead sleeve. It has its non-tip side attached to the inside of the pen body, so it won’t fall off. Multiple attempts and he finally figured out the right width that gives a sweet amount of friction and won’t curl up.
By the way, this guy is such a legend. He’s currently a high school student, and - besides this “E500” - had already DIY’d a fully functional Sakura AT-Matic as well as an FF-Matic in the past, without any machining of metal.
