Thanks guys. The meteorite actually works well as the clip. As I get the material, it was way too thick and stiff, but I found that I could roll it out, and doing that gave it the unique side to side wavy look and it made the material more springy while still keeping the Widmanstatten lines. It is not sealed. The iron meteorite has chromium and nickel, so the properties are somewhat similar to stainless steel. There is a special technique that I came upon to keep it from rusting after the etching, but in normal use, it stays bright without rust. Surprisingly, the weld is strong enough to hold even if the clip is pulled straight out to 90 degrees and yanked with pliers.
The threading is a 2 lead thread that I put very close to the body to prevent your hand from feeling them when the pen is held. It's not a standard diameter or pitch, just something that worked with the dimensions of material that I wanted to work within, and with the drills that I used to drill the cap. No boring is done to the cap, so that is a bit more efficient to make. The dimensions I used also allow turning the whole front section, including two different sets of external threads and one set of internal threads, in one operation from the front.
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