I have some models that have tubes and it's pretty easy to make them much more round and smooth by applying the smooth filter in Blender.
Mesh | Faces | Set Smooth
Is the Smooth feature just a visual treatment or will it actually print out that way? I ask because in object mode and when rendered it looks great, but when editing it is has the same number of faces as it did before the Smooth filter was applied.
Indeed, this smooth only does "normal interpolation" and do not change the actual 3D shape. To have a better visual feel of the 3D printed result, only "Set Solid" should be set, and "Auto Smooth" disabled too (only applied during rendering anyway).