Anti-roll, anti-break core pencil cap (8mm inner diameter, can be scaled as needed)

Participant: Xinbao, Grade 2 elementary school

My desk is slightly slanted, and if I'm not careful, the pencil rolls onto the floor with a snap, breaking the lead and interrupting my train of thought for homework. I wondered if I could make something to stop the pencil from rolling off

I saw that my brother's fountain pen had a cap, and the clip on it prevented the pen from rolling. A flash of inspiration struck me: I should add a cap with a protrusion to my pencil too

Then I wondered if I could add more interesting features to the cap. For example, being able to see how much lead is left from the outside and preventing the lead from breaking when put in a pencil case. After discussing it with my brother several times, we came up with this hollow, anti-break, anti-roll pencil cap

We drew several drafts and finally made this cap. It has an 8mm inner diameter, into which Zhonghua pencils fit perfectly. The lead will be secured and won't break. If it rolls, it will stop after one rotation on the table

My brother said that the current cap has a 10mm outer diameter. If it's too big, try reducing it to 9.5mm. To put it more professionally in his words, it's inner diameter * 1.25 = X-axis width; meaning for an 8mm inner diameter, set the X-axis width to 10mm, and for a 10mm inner diameter, set it to 12.5mm