This is a reproduction of the flower stems from the Playskool Create-a-Flower set.

I made the cylinder design first and then worked out the other dimensions.

Make the width 9.9 mm and then adjust the length to whichever lengths you need.
As my set was missing all but one of them I had to estimate the lengths from an eBay image. I made mine at lengths of 85mm, 160mm and 235mm.

After printing I put boiling water in the sink and dropped them in for about 10 seconds and then put a small curve in them, I used the back of one of my dining table chairs but use whatever you want.

I found using 3 walls and 25% infill made them pretty strong.