3:50 boil, with windshield and lid
Constructed from 2 soft drinks cans scavenged from the side of the road (so I didn't have to actually drink the stuff).
1) On can 1, drill 6 small holes (0.5mm ish) around the edge of the base and 3 4mm holes in the centre of the base (under the penny in the photo).
2) cut off the base of can 1 with about half an inch of vertical can wall. Done by clamping a stanley knife horizontally against a suitable block of wood, and rotating the can against the blade until it's sufficiently scored through to just pull off the base section.
3) drill about 12 4-5mm holes evenly spaced around the top of the sidewall section of can 1 (as in the instructions). Using a pair of needle nosed pliers, bend the bits with the holes inwards to give a fluted edge to the section.
4) cut off the base of can 2 with about 1" of vertical can wall
5) put the can 1 section inside the can 2 section (the flutings allow this as a starter) and press down firmly. I used a whisky tumbler (Esso petrol station freebie, circa 1985) to do the pressing as it was reasonably robust and just the right size (about 1mm clearance all round inside the can2 section. Due encouragement with a block of wood and the gentle use of a mallet was required.
The general idea is that you cover the 2 central holes with the penny, and fill the top with meths and light it. Once the stove has heated up enough, the penny then lifts to allow the bulk of meths to drain into the inside, and falls back to seal the big holes enough to generate a little extra pressure to get decent jets out of the small holes.
In practice, I don't get enough heat transfer back into the base, so this version works better if I prime it with a little meths in a tray underneath and ensure there's a decent windshield to keep the heat in. I'll put the 6 jets a little closer to the edge in version 2 when I get round to making it.