It's a watering can. I use mine to water my plants and fill up the cat water bowl. It produces a nice laminar flow out of the spout and makes a silly snorting sound when it's empty.

The example photo was printed in Polymaker Galaxy Red ASA. I used 3 perimeters and 20 percent gyroid infill. I tested it and it's water tight for over 24 hours. If you want to go crazy, you can try vapor smoothing it.

You can print it with supports on the bottom if you want it to be a little bit nicer, but you probably don't have to use them. In either case, you shouldn't have to print supports on the inside.