I made a little sculpture to test an idea on how to avoid having print-lines show up.

The basic idea is to set up a very slight displacement on the model so that the roughened surface will mask the look of the printed layers.

In blender, you'd add a subsurface modifier, bump it up to 4-6 (whatever your computer could handle), set up a displacement modifier with a noise or cloud texture, then export and slice that model.

It seems to work pretty well, if I wasn't actively searching for the layers, I doubt I'd notice them.

Album of the results:

http://imgur.com/a/v7IlA

 

Interesting.

 

This would make nice aquarium structures, that's what it reminds me of. Kind of natural formations.

 

Now you should find the minimum level of roughness wich can hide seams.)