Blender

Multi-purpose software that is useful in the creation of media. Commonly used to create 3D and 2D computer generated media. https://www.blender.org/

You can use Blender to create 3D models. The 3D models are polygon based in contrast to CAD which is a surface based modeling approach. The main difference is, that you want to create objects out of triangles in blender. You have to 'tell' Blender where to put the vertices and the edges of the triangles you want to show. In CAD you specify the surface as a mathematical equation. This surface can also be triangulated to be shown as polygonial mesh, but it's not that easy the other way around.

(don't get discouraged to use blender, it's more like you will spend another day to port a nice blender model to a cad file by matching the surfaces to your model. starting in blender and creating something worth making a cad file for is way more important)

As the polygons which can be sculpted in Blender are so small, it doesn't really make a difference for our DIY approach. Blender has a ton of tutorials available and there are a lot of meshes already available.

There are plugins for Blender which make it easier to use it for modeling of 3D printable parts.

Polygon modeling has generally two approaches:

• Hard surface modeling / Modifier based modeling
• Sculpting

In the first one you generally try to get the rough shape by modifying vertices and creating a blocky low poly model. Then you apply various modifiers to reach the final result. This creates nice smooth surfaces.

If you want to design something more organic and irregular, you would go for sculpting. This is more hardware demanding because you usually have a pretty high triangle resolution for sculpting. If you want to use these models somewhere else or even animate them you would have to look into retopology.