Ballpoint Pen - Twist Open Without Spring

This is a Twist Open Ballpoint Pen in which all parts can be printed easily by 3D printing(besides refill), you can open it by twisting the cap. This might be the first ballpoint pen with mechanical structure that all parts can be made by 3D printing in the world. The spring is also combined with the parts, so it's no need to buy additional springs. To ensure the 3D printing spring structure works well, ESUN PLA+ filaments, 0.1 layer height, and 40-60% infill density are recommended. the part with spring needs supports, but don't add supports in the nib hole. The partA and partB can be printed with no support. The cap and Turn-out part has 2 versions: normal and tight, you can choose anyone you like. There is another version smaller and more compact than this one that can be bought at: https://www.cgtrader.com/3d-print-models/gadgets/office/3d-print-twist-open-ballpoint-pen-no-spring-required or https://www.myminifactory.com/object/3d-print-3d-print-twist-open-ballpoint-pen-no-spring-required-235664 The refill is the Zebra JF series, you can buy it on: https://www.amazon.com/s?k=Zebra+JF+refill&crid=3754XNSW3FWT2&sprefix=zebra+jf+refill%2Caps%2C501&ref=nb_sb_noss_1 See the assembly Introduction on images, there is a previous version assemble video for reference: https://www.youtube.com/watch?v=emwM9z2lDto The twisting structure is from my old design carrot pen, but this one needs additional spring, if you like it, you can buy it at: https://www.cgtrader.com/3d-print-models/gadgets/office/carrot-pen-rotate-open or https://www.myminifactory.com/object/3d-print-carrot-pen-rotate-open-195681