Do not use these in your airgun or firearm. I and thingiverse will not be held responsible for improper use of this model. Using this to make a cast for lead slugs could be a proper use.

Original lead slug by Bob Boattail

I found a design on eBay for a 30 caliber hollow point slug with a schematic for dimensions. I couldn't find anything about the creator.
I designed this in Blender to be dimensionally accurate to the schematic excluding the tiny section between the far right ring and the beginning of the slope. This is only my second time modeling in 3D (first being the H&N Slug).
I sliced in Cura for Generic PETG (using Overture black) with default settings and Super Quality with 100% infill for an Ender 3 V2 running Klipper.
I then loaded it into a Macavity Arms MA2 magazine and shot a picnic table from 8ft away and it embedded itself to the brim. This seems to be a better design than my previous model of an H&N Slug HP II. It comes out to about 10.5mm length in which I think about 11mm is the max the MA2 magazine will hold.

Again, do not shoot these in your gun. This was for curiousity and boredom. You could possible damage your gun and I'm sure these aren't accurate which poses a safety risk.