Has anyone purchased or used the O'Kief tumblers and if so, what were your results and was it worth the money? I'm going to have a lot of trim this year, more than last year, and instead of giving it to my friends to grind up to make canna-butter I'd like to extract some kief and make some pressed kief/hash. Any feedback would be nice before I go spending 180-200 bucks. Thanks.