Smooth edges on a custom object I have a custom made object (no simple standard mesh, but nothing complex, see below) and lost a lot of time trying to make the edges smooth. 
I tried the bevel modifier, sub surf modifier and bevel by select certain edges (ctrl+B). None of them worked fast and reliable. 


Selecting them edge by edge (very time consuming) left me with problems where two different bevels where meeting.   
the bevel modifier did no work as expected every time
sub surf modifier just created a very distorted mesh. 


This is my mesh (viewed from different angles):







I just want all the edges to be smooth. No big deal...I thought :)
I only succeeded on the front ones.
The point is to imagine the several angles your mesh will have to be bent.

It can be composed of an initial shape and 3 modifiers : mirror, simple deform and subsurface.


Here, there is a final curve : the "U" general shape.

But before that the mesh can be flat. Here the mesh before using the two final modifier (simple deform and subsurface) :



The main point is to use quad everywhere so that :


Edges are in the good position to be bend to the "U"
Subsurface modifier works well


Notice the selected line on the screen capture : it is here to preserve the outer edge and avoid the subsurf to deform it too much.

As you want to print it, you may want a "lot" of subdivision.

Here is the modifiers stack :



Here is the blend file