Based on TrooperOrange's excellent work, which in turn was based on Clarkerubber's also excellent work, I have added a few improvements.
1) The bottom bowl piece is threaded so it cannot fall off.
2) There are no 90 deg overhangs, so it's easy to print.
3) The bowl is deeper so it will hold more.
4) It's taller because the top had a tendency to cant (the technical term for this is to become cattywampus) if there were too many herbs in the grinder.
5) I added guide slots in the housing with matching tabs on the grinder plate because it was difficult to slide the plate in without it canting.
6) Used rifling on the outside because it's easier to clean than knurling and is also easier on the hands (and on sponges). (Clarkerubber also showed rifling as one of his choices.)
Another feature is the flared holes on the bottom of the grinder plate to minimize clogging.
After user comments and testing with an herb commonly available here in Colorado, I have added two new grinder plates. The original grinder plate had a 1 mm gap between the blades and the plate. In the new plates, the gap is 0 mm. One of the plates is inverted with the flared side up. Users can judge for themselves which they prefer.
I have also added two new pieces: a Cap and a Funnel. Both can be screwed to the bottom bowl. The Cap can be used to further mix the ground herb by shaking it or just for storage. The Funnel makes it easy to pour the herb into other containers without spillage.
If you have previously printed parts from last week's publication--no worries. Those parts haven't changed.
MG Chemicals PETG
Blue & Orange
The Funnel should be inverted before printing.
I printed TrooperOrange's Turbine grinder and then reverse-engineered it into FreeCAD. The hardest thing to figure out was how to model the "turbine" blades. You do these by starting with a solid cylinder and then using a subtractive cylinder of the right radius and angle to produce the desired result. You then use a polar pattern feature to generate all the blades.
On the bottom I used a subtractive ellipsoid (think egg) to make the bowl deeper.