ok.. get a pill bottle, like an aspirin bottle or sometthin..
punch 2 holes in it the size of the plastic tubing... put some tubing into one of the holes.. that'll be ur blowpipe.. the other is the carb...

get a beer bottlecap n drill 4 small holles..
get 2 washers n glue them together
slice a piece of piping, that'll fit ur nugget, and put it ontop of the washer.. then put the washers inside the bottle cap.. it'll make kindalike a pre-gaschamber..

put a bigass hole in ur pill bottle cap, but not bigger than the bottle cap..
glue the backs together
and vuala.. crush up some ice and the shit will be AMAZING