I am still having issues with Cura slicing software honoring some of the model's features. The red areas (see pic) are problematic. I plan to simplify the model, but keep its outer shape, to fix issues like this.
The hardest parts are behind me (like the sheep's interior void and modeling the two screw features). For the needle compartment, I scaled the screw's interior piece down by 0.5mm on each side (-1.0mm on X and Y axis).
Davin, these are so cool! I'm bouncing, here! I love the dimensions, and the thimble and needle & thread spindle are perfect! I'm confident you will get there, soon! It's fun watching you and Dave essentially racing to get your respective designs figured out.