I just wondered if anyone else had done anything similar?
I will be using it on canoe / camping trips.
To be honest, you are not going to get it right first time. So I recommend having a go yourself, unless your mate likes the project himself. I made two standard sized Nimwald Dandy's. One out of 0.9mm stainless,which is FAR too heavy but was easy to obtain and one from 0.4mm titanium which is so light that your pan scourer probably weighs more. (Well 4oz in truth)
However, they are both just cooking stoves. They burn out the instant that you've got your food to temperature. If I do another it will be out of thin stainless (0.7mm if I can find it) as it's cheap and easier (ha) to work than Ti. I certainly wouldn't pick Ti unless you are lightweight backpacking. I would also make it about twice the size, which would be about 4 times heavier for the same thickness of material (significantly heavier than the one that's "too heavy").
That is of course why I say that you won't get it right first time. There is NO perfect universal firebox.
0.7mm stainless should be just about possible to cut with aircraft snips, which makes things a LOT easier. A dremel slot cutter is also worth a investment. Drills just don't work well and while a jig saw works, you have to drill holes to get the saw in when cutting slots.