Well, I have no idea how deeply you have read into the matter.
I would like to point out that I don't draw octagonal things, but the inner hairpin including the recess for the logo and the exact dimensions including the end cap, and all in one piece.
If you take a closer look, you will notice that the workpieces shrink by a few tenths of a mm - this depends on the density, the material and the temperature.
You have to take these things into account when drawing, otherwise you will end up with a part that you can throw away after 4 hours of printing.
As I said, only with the 3D drawing can you slice a printable version in the printing program of the 3D printer and then print it.
I ONLY charge this initially high amount for the drawing - if you print 20 of them, the unit price is negligible.
I don't think the result will be a disappointment.