Basically, real simple. I used a resin mold MC-4. Woodnwhimsies has them. This will hold 4 of the balls, tightly fitting. Some will stick out of the top, but I just kind of mashed them down. Then I mixed the resin and blue coloring, poured into the mold and let sit on my "running" drill press, since I don't have any chamber or vacuum, pressure chamber. With this, I get 2 blanks for a Phoenix or Sierras. After cured, I just cut it in 2 pieces, lengthwise. Drilled the hole and wallah! Turned that buggar down.
It took a lot of gap filling with CA and some of the turned blue material filled in nicely.