As of the latest patch, SketchUp crashes immediately when I scale below 6", or when I explode components in less than 1'. Basically, it's now incapable of producing small components. While irritating, this did lead me to discover a couple of useful tools.
Netfabb Studio Basic - This is a free program that accepts Collada (.dae) files from SketchUp, scans them for problems, resizes, and exports to .stl format. It even has a basic mesh fixing algorithm that can fix simple problems with your mesh.
This is also great if you want to make an injection mold for your models instead of 3d printing. The interface is minimal and easy to learn, with only a few options that are pertinent to the design pipeline.
Sculptris - Another free program from Pixelogic, the makers of zBrush. This is an amazing tool for producing organic models very rapidly. It is slightly more difficult than SketchUp, but leagues easier than Maya or Blender for making organic models. Though there is a slight learning curve, there also are piles of tutorials for making just about any kind of model you want. Sculptris exports to .obj, so it can be loaded into Netfabb, correctly sized, and (if necessary) exported as a .stl file.
Another great benefit of Sculptris is that you create models in the same way you would clay or putty, so a lot of the same techniques can be used. The downside is that it has very few undo steps, so it's possible to destroy a model on accident.You'll want to make alternate saves at regular intervals to avoid this. Once I get the hang of Sculptris, I'll do some blog updates with tutorials, renders, etc etc.