At a certain point, you will realize that the part you need is not available online, and your laboratory will enter the second phase of owning a 3D printer: Designing. I cannot stress enough how significant it is for scientists to have at least a basic knowledge of 3D design, not only for 3D printing but also for making attractive figures for papers and presentations. Learning 3D design may look like a difficult task but, trust me, it is not that difficult, at least for simple designs. If you can sketch something on paper, you can design it yourself on a computer. By designing your models, you unlock the full potential of 3D printing. Now, you can produce parts that are not commercially available, that are a perfect fit for your application or laboratory, or that are replacement or enhancement parts for other instruments there. This is the true power of rapid prototyping; you can design, print, test, and redesign an object in less than one day without ordering the part from a specialized online service -which, typically, requires weeks. For example, modifying an expensive centrifuge for separating large volume blood samples with a simple 3D printed add-on. Creating something from scratch and having it in your hands a few hours later is an incredible experience.