It's possible your original Blender design had an issue. Blender is not always kind to 3D printers.

The first thing I would tell you is to stop using cubic infill, it is evil. It never always causes me failed prints, especially larger prints. Nozzles often tend to drag across the previous layers and can easily cause failed prints. I can even hear the nozzle hitting the infill as I print. I often recommend gyroid as a good all around infill pattern.

How to think about this design problem.

I look at it and I wonder, does the rolling pin need to be supported full length? A wooden rolling pin is ridged and only needs minimal support on the ends. So I might just design the cradle only at the very ends. And then design the middle to be a simple flat that connects the two end pieces. I might even skip the middle altogether and just print the ends. That saves the most material and time and still does the job perfectly.

When it comes to slicing your print, orientation matters. How you support overhangs can be tricky and often compromises must be made. While I will use the auto supports as often as I can, sometimes you just need to use paint on supports to get what you needwhere you need it. Pay attention to the top zed support gap. The defaults are never right. I always open them up more. With a .40mm nozzle, I use a .265mm gap. For a .60mm nozzle, a .365mm gap.

You might even need to print your parts at an angle. Often tipping the part at 30 to 45 degree angle can make those nasty over hangs completely printable without supports.

And this is only a good beginning. How fast you might print an overhang matters, the amount of cooling fan can affect the over hang, lots of fine details that you will learn about as you keep doing this.

Good Luck and never fear making a mistake!