In my previous question, I asked if there was any means, in RAW or RAI, DnD 5e, for a character to create a druidic focus out of a living tree, as described in the PHB:
A druidic focus might be a sprig of mistletoe or holly, a wand or scepter made of yew or another special wood, a staff drawn whole out of a living tree, or a totem object incorporating feathers, fur, bones, and teeth from sacred animals. A druid can use such an object as a spellcasting focus.
And although interesting alternatives were presented, there doesn't seem to be any means by which a druid could do this in the scope of that question.
I am looking instead for a means to do this in a previous edition or different system, that I can then adapt to my game. Bonus points for suggestions on implementation.