best way for the kief extraction imo.. is to take the green freeze it in a mason jar 24 hours then once it is frozen you can take a wooden spoon and stir the green inside the jar (much easier to grind this stuff once it's frozen) then add some dry ice cover with a nylon or bubble bag and shake it..
Theres some great info on here about Dry Ice Hash. Many threads. It would well be worth it to read. Dry Ice can produce some nice kief, but it can all so produce a large pile of green shit if you over work it.
My experience...
You want to use DRIED trim, frozen is fine but the dry ice freezes it.
Shake your first run for about 20 to 30 seconds for the best stuff.
Next run shake for another 20 to 30 seconds in a spiral. The best stuff is in the middle and it gets worse as you circle outwards.
Use the first run for full melt and the second run for edibles.