The antidote is physostigmine or pilocarpine, the same as for atropine. -Wikipedia

Also nicotine is a weak antidote to atopa alks generally lessening the effects in only the smallest amount IME.

1- Collect datura flowers and seed pods.

2- Dried and powder, coffee grinder works well.

3- Acidify water to Ph 2.
-Hcl 30% ~10ml/liter.

4- Mix in powderd plant material and heat to 50 deg C for ~20-30 minutes while stirring.

5- Remove heat and allow to cool. Cap jar and wait 12 hours.
-Repeat 1-2 times for improved yeild and combine fluids.

5.5- If you used just flowers you probebly wont need to defat, otherwise it would be a good idea.

6- Slowly add Lye while stirring. I reccomend only adding ~1/16 - 1/8 a teaspoon by sprinkling slowly at a time and waiting 2-5 minutes for a haze to form.

7- Once all of the crystals are settled to the bottom remove as much water as possible with a baster or whatever.

8- Pour onto a evaporating dish and allow to dry. Heat probebly wont hurt.

Delivery:
Isoprpyl works good and can be saturated more than ethyl alcohol as a delivery system. Just let it dry before smoking.

If you choose just powder then only use about 2-3 or less to begin with. Generally extracts of this tech will require about 10-20 mg, although this is ASSUMING a significant loss. If you is more pure than using that much could EASILY cause bad effects and possibly death(a COMMON occurance with the atropa alks).

Smoke slowly and stop when it starts to hit you our else it may become uncomfortable real quick.

Oral dosing is probebly not the best way due to the duration and more erratic behaviour of the atropa alks.