Finally took some photos of my pen blanks. I have two flavors. One with angled disks and the other plain with no pattern. I had these made not only in the new HP plastic but also red SF and polished metallic plastic.
Above 2 photos, black and gray are HP plastic and red is red strong and flexible.
Above 2 photos, black and darker gray are HP plastic and lighter sparkly gray is polished metallic plastic.
Some impressions of the parts... The HP gray plastic is a bit color mottled and not as consistent in color as the polished metallic plastic. This mottling is at a larger scale than the finer grain details but it isn't terrible and actually adds a bit of interest for something like a pen body.
The disks are a bit fatter for the HP plastics, and that means the gaps between the disks are a bit smaller.
The finishes of the no-patterned tubes feel mostly the same. The polished alumide (old polishing) is a wee bit smoother although there are still some detectable bumpies when you run your finger over the surface. I plan on putting these on a lathe to see what happens with a cutting tool and various polishing media.
I also measured the lengths and weights of the tubes. All were designed to be 52 millimeters in length.
Angled disk tubes
red SF 3.7 grams 52.13 millimeters
gray HP 4.5 grams 51.90 millimeters
black HP 4.6 grams 52.00 millimeters
Smooth tubes
polished metallic plastic 6.7 grams 52.06 millimeters
gray HP 5.1 grams 52.03 millimeters
black HP 5.2 grams 52.04 millimeters
As I recall the tubes were all slightly over-sized in length by a smidgen to allow some sanding if necessary to flatten the ends for better mating with pen hardware components in the pen kit. In these cases it's the rounding or cupping of the tube end surfaces that will probably need a few light passes on a fine grit sandpaper to get them flat. But I'll know more after I start to assemble them.
One more thing. The insides of the printed tubes were a little different based on how the 7 millimeter brass tube from the pen kit fit inside of the banks.
For both the red SF and polished metallic plastic the brass tube slides in easily, although for the red SF the hole might be a tad bit too large and there's a little wiggle of brass tube when inserted. That's easily fixed with a few light lines of thin paint applied to the brass tube before assembly. We're probably talking about 0.001 to 0.005 thousands of an inch excess of inside diameter and that's below or near the print layer resolution of the printers.
The diameters of the HP plastics are on the very tight side. I couldn't stick the brass tubes into them without risking them getting stuck so the HP tubes will need a few light swipes of the inside hole with a small diameter round file.