Young children typically love toys that represent what adults understand to be principles of physics. They enjoy playing with toys that float, fly, slide, roll, etc., and it's an important part of learning. Boats demonstrate buoyancy.

In turn, I've created what appears to be a simple rowboat with two benches inside, but is so much more in the imagination of a child. They can use the benches for other toys to sit on, or as separators as they move toys from one place to another. The boat is small enough to fit in a tub with other toys, but large enough to not lose interest. Edges are rounded and softened.

The boat has a toddler-tested 2mm thick wall, thin enough to minimize filament and print time, but thick enough to be rigid. The photograph required me prying it away from my little one, because the second he saw it he wanted to fill the sink with water.

In terms of printing, 0.24mm layer height is fine, and can probably go a good bit more, with some loss of the lettering. You'll just have to check your slicer to see. For infill, I wouldn't go more than 8-15% with 2-3 walls. Any strong infill such as gyroid would be best. You may wish to paint your own z-seam. No supports. It is definitely scalable and all angles are printable by FDM/FFM.