Printed vertically in natural PLA. Turned out pretty much perfect - its a great design! Works and sounds great, very similar to the wood train whistles I used to play with as a kid.
The only downside, in my opinion, is the 3 holes are kind of hard to blow into at the same time because of the triangular shape. You kind of have to get your lips around the entire mouthpiece to make a good seal, so it's harder for my young son to operate. It would be great if it had a single air hole to blow into like the wood versions I had as a kid. But no matter, I love that classic train whistle sound!
Printed vertically, flipped 180° so the mouthpiece was touching the buildplate.
2 perimeters. I tried 3 to make it as airtight as possible but 3 created small gaps between the hollow tubes and the outer wall.
The holes on the mouthpiece really decrease the surface area sticking to the buildplate so I used a brim just to make sure it didn't tip over.
It printed in about 4.5 hours at 50mm/s