I've been practicing and believe I'm finally achieving results worth sharing. If this appears to be popular I'll add more from my large collection of shells.

Scanned with a CR Lizard, repaired in Blender 4.0, sliced with Cura 5.6.0, printed on my Ender 3 S1 Pro with Zuff cooling. Printed at full and half scale with Polymaker green glow in the dark PLA.

0.2 mm layer height

3 walls

10% gyroid infill

tree supports

brim

SLOW (overhangs @ 30mm/s)

The model naturally lends itself to printing in an upright position, as shown in the screenshot and on the printer. That's a 45d shift on the Y axis. However, I tried a print with supports oriented as the model is in the stl and it was OK, in some ways it was looking better, but it failed thanks to my impatience and I haven't tried another. This ‘vertical’ position is tricky, but I've succeeded with 3 out of four prints so far, and the one that failed was again, due to my impatience and foolish belief that because my prints work out at 60 mm/s doesn't mean I can print at ludicrous speed. You might want to play with which two spurs you want to use as legs of a three-point buildplate touch if you're not comfortable with only a couple of small lines contacting the plate.