A sustainable hashish resource

Two concerns- First the trichomes you are looking to harvest would still be underdeveloped (aka clear heads) and make for an odd racey high. Second, I have my doubts the plants are going to appreciate a 20 minute submersion in ice water enough to reward you with a second pull, if it even produced additional trichs at that point. The plant would continue to mature and die if it did manage to survive. Even if this did work, it would be a labor intensive proposition and require a bunch of those tiny plants for even a small amount of hash. Your ice water pull would leave a lot of unextracted product inside the buds that you would more than likely loose after mold sets in those buds and they begin to rot from the inside out.