Sliced in Cura 2.7.0, 215°C/55°C, took 13 hours to print at 110.5% and stands 105mm high. The inner and outer walls are 3 layers thick with a hollow gap between them.
The only place fill is needed is between the outer and inner base I chose concentric infill at 16% so that it wouldn't fill in the walls of the vase going up, but the concentric wasn't very reliable looking (see the photo); I don't recommend it. Sure, it worked on this print, but I think there was quite a bit of luck involved ;)
To support the 'handles' and holes, a zig zag support at 70° overhang worked perfectly and can be easily pulled off the inner floor with pliers and (even better) a 90° scriber hook (helps if you have slender fingers!)
All in all, it's a wonderful vase - ingenious design by Virtox. And yes, it's watertight, as my fresh home-grown roses prove!