I made myself a tumbler a few years ago.
It worked well but dry ice is hard to find around here.
One place I can buy it costs me $6.00 per pound and it's more like dry frost.
The bucket idea is cool if you can find dry ice for cheap.
http://www.youtube.com/watch?v=1buSgDNfGFQ
I made a tumble from the idea:
https://www.rollitup.org/do-yourself/409110-diy-hash-tumbler-poor-mans.html
My old, dead furnace had a humidifier attached that still worked.

First I cut it half.
I took it apart and cleaned as much lime scale from it.
I put 4 small wood screws through the plastic humidity wheel, cut a piece of plexi glass and used rubber bands to hold the glass in place.
Not sure of the size I used but hot glued the silk screen around the wheel.
Loaded it with a bit of trim and dry ice, screwed the wheel on the motor and let it run.
Had some nice kief in a few minutes.
In action!
I put a cassette case under the wheel for this experiment and collected some kief.
All in all I would stick with the buckets and bubble bags.
Seems a hell of a lot easier.