I generally avoid single-purpose tools, but after ruining a couple of tools puncturing MSR IsoPro canisters, I asked for a Snow Peak Kuwagata for my birthday. It makes a nice squarish hole with no fuss.
I tested the FlipFuel fuel transfer device and it works well to consolidate partly full fuel canisters. It left about 6% of the original contents un-transferred (13-17 g), roughly enough to boil 3-4 cups of water. I’m OK with that performance. I started with six canisters ranging from 22% to 55% full and ended up with three canisters that were 74% to 81% full and three punctured, empty canisters in the recycling bin.
Most Casual Observer 