Hollow Extensible Rod

目前并不是一个完整的版本，我期望能够使用镂空杆随意组合（就像搭积木一样）。目前仅支持实现延长而不支持转角度。你可以打印很多个本模型拼接起来形成长的杆。（可用于做任何杆可以做的事情，当然我的最终目标并不局限于此）。镂空的原始设计来自我的另外一个设计：It's not a complete version yet, I expect to be able to assemble it at will using the hollow rods (like building blocks). Currently, only extension is supported but not rotation. You can print multiple copies of this model and join them together to form a long rod. (can be used to do anything a rod can do, although my ultimate goal is not limited to that). The original design of the hollow is from another design of mine:https://makerworld.com/zh/models/521030#profileId-437500 而添加的螺纹则来源于这个网站的螺丝生成器工具。为什么不直接在建模软件里面产生螺纹，因为这会涉及比较大的计算量，以及不够灵活。像freecad软件目前报错率本身就很大了，如果在里面设计螺纹极易崩溃。The added threads come from this website's screw generator tool. Why not generate threads directly in the modeling software, because this will involve a relatively large amount of calculation and is not flexible enough. Software like FreeCAD currently has a very high error rate, and it ca