This is a quote from Wikipedia:
QUOTE
Charas is made by rubbing ones hands through the flowers and is long, tedious work. The resin sticks to ones palms and by the end of the day one has harvested perhaps 8 or 9 grams of charas. The faster one works the lower the quality of charas. Hence to make 'cream' it is necessary to go very slowly and it is only possible to make a few grams a day.
I'd be really interested to know if anybody has tried this or knows anything more about it.