Hi Mala,

re:
> booled or trimmed (not sure which operation is here state of the art - I do not yet exactly the difference)

If you have a solid then booleans are good, the booleans cut pieces up and then decide which pieces to keep based on which solid volume they are contained inside of.

If you have open surfaces then that's usually when you should use Trim - Trim doesn't automatically decide which pieces to remove, you have to pick the pieces you want to get rid of.

On your model I'm not sure why Filleting doesn't work but if you break the object apart into individual surfaces you can use surface/surface filleting on it by selecting 2 surfaces at a time instead of edges.

I can help you do that, what radius do you want?

- Michael