Take a detailed model and make it suitable for 3D printing?
I would recommend "The Maker's Muse" youtube video channel.

In particular this video Fixing impossible STL's with Meshmixer 3.1.118 BETA might solve your problem.

Few other videos which might help:


How to make Engineering Assemblies 3D Printable using Meshmixer
Add smoothness to your meshes using remeshing! 3D 101
A Detailed look at Processes and Profiles in Simplify3D
Tidy up your prints with the Modifi3D
How to Print Bigger Things - 3D Printing 101