I had thought about making a smaller stove, same diameter but shorter so I made a new firebox and outer by cutting the smooth section off the base, removing some of the ribbed section and pressing the smooth section back on, I did that for both cans. Again I used the mesh grate but left it loose in the bottom of the firebox. One other thing I discovered was that if I flattened the inner lip at the top of the firebox (the lip is left when the pull-off lid id removed) a trangia burner fits perfectly and works as a back-up. The Trangia burner can be packed away in the base of the stove as the grate being loose simply moves up out of the way. I made a slightly different windshield/potstand but it probably doesn't make much difference. I tried an Alpkit Mitymug 3/4 full and managed a strong rolling boil in about 12mins, not really fast but I wasn't using a secondary foil windshield, the temperature was below freezing and the firebox is pretty small.
Reasonably happy with the result but there are a few modifications I want to try on the mk4 model.
Mesh Grate, about 20mm. Slightly smaller would be better as the kindling has a tendency to fall through.
Alpkit Mitymug, Rolling boil.