what you need:
a small to medium glass jar/bottle with lid
broken bits of glass or dishware
nails, screws, tacks
pins, needles (anything sharp and harmful-brambles or thorns?)
hair, your own urine, semen or menstrual fluids
a bit of dirt
purifying herbs such as Rosemary, Sage, Yarrow, Bay, Pine
(Mama Moon adds: I use onion, garlic and basil too)
and still others add:
a spell written on parchment in dragon's blood ink
herbs for protection
Assembly is up to you, it can be simply filling the jar with sharp objects and peeing into the jar, then sealing and burying or you can design an entirely more elaborate ritual.
Basically however you decide to fill this, once filled the jar is sealed shut and buried. I buried mine in what I hoped was an area that would remain untouched. Once this is unearthed you need to make another.
I have read that one can simply bury this in a planter or near the entry of one's home (from "Green Witchcraft" by Ann Moura (Aoumiel)) I buried mine out in a field I had hoped would remain untouched by developers..so far so good, but I imagine I should start a new one as *progress* is taking over and this rich farmland is becoming developed.
Bury this sealed jar at night (though burying it during the day worked just fine for me)...you may want to burn incense nearby, as you assemble it allowing the smoke to find its way into the jar, as opposed to the burial site to prevent fires.
You may want to add a spell and chant of protection while you bury the jar.
Aoumiel's book also suggests making a new one yearly at Lunasda.