Round fillets for surface only

 From:  Frenchy Pilou (PILOU)
8270.2 In reply to 8270.1 
Of course yes! :)
Your volume must be a volume

Select external principal edges's handle then call Fillet
Select internal principal edges's handle then call Fillet

If needing
Select little drawings rectangular + sinuous curve then call Fillet

PS and rectangular must don't touch the internal Princimpal edges!

EDITED: 17 Jan 2017 by PILOU