You can make your own powder by drying henna leaves in shade. It might take weeks for them to dry to a crisp and you need to grind them thoroughly. You may also buy henna powder from the market.
 
Take...
  
1. Henna powder seived through a muslin cloth.
2. Well strained strong tea decoction.
3. Eucalyptus oil (a few drops).
4. Strained lime juice.
5. Sugar(1 table spoon)
  
Take the henna powder in a bowl, add the tea till it becomes a thick paste (similar to a dough). Add eucalyptus oil, sugar and lime juice and mix well to make it into a smooth and thin paste. Leave it covered over night or during the day if you prefer to apply in the night. Make a cone... Take a thick plastic cover (milk cover is best in India). or use any thick freezer bag - cut it into 7" X 4" rectangle. Twist one corner of the cover to make a cone. Tighten the tip to make tiny hole. Hold the tip and fill the paste and tie the broader end tightly with a thread (the final cone looks like a carrot with leaves). You also get ready-made cones from the stores.