The one I tried to make several times was this, it's supposedly more efficient (or something) but perhaps I'd have better luck with a normal one. Better drink this Guinness I've got sat on my shelf then!
Edit: this one is much better than the last one I made. Took more time with the widening part and also sanded it down a bit. I used the lid off a golden syrup tin, slightly bigger and heavier than the top of a tin can but no razor sharp edges which is nice
The one I tried to make several times was this, it's supposedly more efficient (or something) but perhaps I'd have better luck with a normal one. Better drink this Guinness I've got sat on my shelf then!