How to scale a mesh evenly without causing the faces to intersect? I'm still pretty new to Blender and 3d modeling in general so I probably don't have the right vocabulary to describe exactly what I'm trying to do, but I hope the question is clear enough. 

What I need is to scale a mesh evenly but without creating intersecting geometry as shrink/fatten tool does. In other words I want the scaled mesh to fit neatly inside/outside of the original unscaled one.

Here's a mesh off thingiverse that is complex enough to illustrate the issues I have when using either scale or shrink/fatten tools.


As you can see the duplicate mesh that is simply scaled along the axes naturally doesn't fit inside the bigger one at all, and the one edited with the shrink tool while being kind of closer to what I want intersects both on itself and with the original mesh.

I've been stuck with this for a while now and would be grateful for any tips you can provide.
ALTS is to scale along the Normals and if your vertices are all on the same plane they should only move up and down. If not, select all and scale the Z axis to Zero, and then remove doubles - just to keep things simple.



You could start by trying to scale the model just on the X axis and then the Y and see where the distortion starts. After that you will probably need to proportional scale - and it might be handy to turn on connected. You can also move and rotate proportionally.



What you might be thinking when you say 'scale evenly' is probably more correctly offsetting. There are tricks and work-a rounds but most software I have come across runs into trouble with intersecting surfaces.