I took a pen making course a year ago and found myself looking for new materials to use to use as pen blanks. Most people use wood or cast acrylic/polyester resin blanks, but anything that can be turned on a lathe has probably been tried by someone. I've been experimenting with many of the Shapeways materials so far except for metals.
One of my experiments has been using the full color sandstone (FCS) process to design full color blanks with interesting patterns. If you are good enough at woodworking you might be able to do some multicolor designs by laminating various materials together but that's a lot of work. I don't have enough patience for that and I have limited access to a friend's woodshop equipment to develop new techniques.
You might think that the FCS process wouldn't be so great for making pens, and while it has some limitations it turns out that it's a lot better than I expected. The outer surface of the FCS material is not so great with respect to handling. It doesn't like moisture and is a bit grainy. But sometimes more beauty lies just below the surface. The surface color pigment layer of FCS appears to be in the range of roughly 25 to 30 mils or so in thickness. If you remove about half of the surface pigment layer you end up with a nice colored material that can be sealed to form a nice pen body. It can be handled without damage as long as you don't beat up your pen by hitting it on hard corners or dropping it on the floor.
One way to design your FCS tube is to make the outside diameter larger than the final dimension by roughly the thickness of the pigment depth (to remove half of the colored thickness on the lathe). The inside diameter is determined by the pen kit's brass tube outside diameter or process minimum wall thickness. It turns out that every pen kit out there likely has finished blank wall thicknesses that are less than the minimum wall thickness design rule for FCS. So you need to design the inner hole diameter smaller and then enlarge it. I use a round hand file and carefully rotate the blank as I file to evenly enlarge the hole and keep it centered on axis. If you go off axis you may machine through the color layer when you lathe your blank. I have been using the 8mm metallo pen kit available from Penn State Industries because it has a thicker finished blank wall thickness than most other pen kits. This pen has a clip on the prefabricated cap so there's no danger of the clip damaging the finish of the pen with use. A thicker pen blank wall also means less work enlarging the hole. It takes me about 15 minutes to manually enlarge the hole with the round file. At first I tried drilling a hole in a solid cylinder blank but I could not center the hole well enough, you must be VERY careful when clamping the blank while drilling, and the blank nearly doubles in price because of the extra material. It's not a good method in my opinion. Here's a photo that shows how the blank is prepared before turning on a lathe.
I oversize the blanks by 10 mils on each end as an allowance for the sanding step. In addition I lengthen any color pattern on each end so that any regular repeating pattern is correct after sanding. An effort needs to be made to center the brass tube in the blank when gluing it in place. Use standard pen maker's CA glue or a two part epoxy. After the glue is dry the excess blank material on the ends of the blank need to be sanded down flat to the brass tube. I sand by hand using a sheet of 400 grit sandpaper and check my progress with a pen bushing for that kit to make sure that the sanding plane is perpendicular to the long axis of the blank. You could probably use a disk sander, pen maker's pen mill, or jig on a lathe to square off the ends of the blank after a bit of experimentation.
If you're a pen maker you likely know what to do on the lathe. Briefly those steps are:
1) Using bushings appropriate for your pen kit turn the pen blank down to the finished diameter as determined by the diameters of the pen bushings. I use an Easy Wood tools carbide radius cutter which is great for FCS and other Shapeways plastic materials.
2) Dry sand the blank lightly with up to 600 or 800 grit sandpaper on the lathe. You can also use a micromesh product after sanding for a final finish if you do not plan on using any sealer as a protective finish layer. (I have made a pen with no protective finish but have not used it enough to determine long term ruggedness. A layer of pen maker's wax applied on the lathe may also be sufficient for decent protection from handling)
3) Apply a standard CA glue finish, sand it, and micromesh finish it for a glass-like clear protective finish. I generally apply 5 to 8 layers of medium CA glue.
4) Assemble your pen using a pen press. Follow the instructions that come with your pen kit. For FCS blanks I make sure to always use a bushing on the open end of the blank when pressing a pen part into the other end. This helps to protect the open end of the blank. If you don't have a pen press you can use a large C-clamp with wood or plastic placed on the clamping surfaces but you must be careful to not crush your pen parts.
And here's an example of the finished product, which as far as I can tell must be uploaded to a separate post. To be continued!