I use a length of guttering bought from the Big Box store. Sealed the ends with the caps sold with the gutter with silicone only. I boiled the (well water) over a two burner propane BBQ grill. City water can cause problems so store bought distilled water is recommended. My well water works fine. Small parts can be boiled in an old sauce pan, I go at least 10 minutes, give it a little more if I'm in the mood. There comes a point where it isn't going to get any darker.
There is a method of using PVC pipe vertically, the bottom sealed with PVC cement and a cap. The sealed barrel is placed in the pipe and boiling water poured in, repeat as you see fit.
What you'll get is a black coat with brownish undertone, there isn't any blue in it. It is very durable.
dave