I obtained two stainless steel mugs, as close in size as possible. One is a double wall, the other is a single wall.

I cut the bottom of the double walls in quarters, leaving some structure . I also cut some vent holes near the top. I use a salmon can for the stand, punctured with a church key can opener.

I use a small coffee can punctured with a church key can opener as the stand for the single wall.

Into each I place a tab of Esbit. Into each cup I add two cups of cold water from the fridge, about 45 degrees F.
The flame keeps going out in the coffee can/single wall stove. I soon realize I need to create an air gap at the top so use a nail. We are 3 minutes in. I repeat the coffee can/single wall stove to verify the time.

coffee can/single wall stove
rolling boil: 8 min 15 sec to
gentle boil: 10 min
simmer: 11 min to end of tab, about 11:30

salmon can/double wall stove
rolling boil never reached, near boil around 10 minutes.