I designed this modern vase consisting of two parts. The outer part is printed in vase mode and prints in about 4 hours. To be water tight I added a inner part which is printed with 4 wall perimeters (2 hours print time). I printed everything in Bambu Lab PLA (matt for the outside). As far as I can tell, the vase is water tight and pretty sturdy.
Please also check out my other vases: https://makerworld.com/en/models/407515#profileId-309513 https://makerworld.com/en/models/147573#profileId-160990