You can get a lot of free 3D models for components from 3dcontentcentral - its mainly a SolidWorks user upload\sharing site but there are a lot of components on it.
Yes, 3dcontentcentral has a huge database of existing 3d models, which includes many 3d parts, even some rare to find connectors for example. Its a great site, where everyone can share their own created 3d models.
By using 3dcontentcentral and the (very) basic 3d modelling options within Altium Designer i have been able to avoid the need to use external software to create my own models. At least up until now... A simple example:
![](https://s25.postimg.org/63267zvt7/PCB3_D_Altium.jpg)
The advanced 3d models shown were mostly downloaded from 3dcontentcentral and the simple 3d models such as the pot and heatsink were created from within Altium Designer.
But because i have some experience with Sketchup, it would be interesting to learn how to use sketchup to create/edit existing models and then export them to altium. Altium by itself is just way to limited when it comes to creating rounded shapes and non rectangular shapes.
I think the biggest problem with all these 3d tools is that there are just way to many 3d file extensions out there. That makes all of the tools very incompatible with each other. The same of course goes for pcb/schematic file extensions, but that is another story.