Both are easily worked with files and sandpaper. I would suggest drilling the holes on SLOW speed (I used traditional drill and wood spade bits) cleaning as you go. If you can find some-one with a wet saw it speeds up the roughing considerably. Both will shape to nice crisp, sharp edges if you take your time.
Catlinite seems to work better when fresh, as it seems to harder a bit with age and heat.
If you are using catlinite, work outside away from the house and make sure you clean yourself up well. If you don't you will be dragging red dust into the house and really annoying your significant other. You will find it regardless no matter what you do.
Don't plan on using the files for anything else afterwards as they will dull quickly.
Once done with the final sanding, warm up the pipe bowl and rub well with grease of beeswax. Polish with a piece of canvas, carve a stem and enjoy the fruits of your labor.
Black Hand