I will keep this as short as possible. (I have to go to work tomorrow.) If you look at the picture below (thanks Fenlander)
you should just be able to make out a stick lying across the top of a wood stump and a cloud of smoke in between (coming from a rather damp tinder) and Sam blowing into it. A few seconds later the smoke was accompanied by flames. So what is going on? Well, we think that between that stick and the flat surface below has been formed a chamber that traps the heat in. This allows damp tinder to be cooked dry before it starts to burn with a flame.
So, probably you could simply put your more traditional nest tinder in that space, just balancing or leaning a broad stick on the top. No need to hold it in your hands, and because it is near ground level less risk of hot sparks floating about to burn clothing. No need to keep it compacted either because the top stick does that for you.
However, what was in that space was in fact some shredded leaves on this occasion, because that is what came to hand. The "oven cooked crumble" tinder seems so far to be so efficient that it can probably work for any vegetable matter that is physically able to crumble when rubbed between the hands.
So, I would take anything to hand that is dry enough to pass this test. In woodland the leaf litter off the ground seems suitable if it passes the crumble test. Too damp and it just crumples up like a rag. So I am not just taking any leaves. I am taking mostly the topmost layer, and casting about for leaves that have been protected from direct rain by being under dense trees or even awnings etc if available. I take a few handfulls and place them beside a flat surface. I then take a small amount at a time and rub it between the hands over the flat surface. With leaves you generally get some bits and leaf skeletons. I tear the leaf skeleton a bit and rub again to release more bits. I treat most of the collected leaves like this.
Then with just the tips of my fingers I lift off anything except the tiniest bits. Then I carefully collect these tiny bits (gold dust!) and make sure I have enough to form a ball at least 2cm (an inch) across. The gold dust collection is carefully moved to one side and all the remaining tinder, both the shredded leaf skeletons and any that I did not shred, is made into a rough pyramid/ cone in the centre of the chosen flat surface. Then I lay a piece of wood (or two smaller bits) on the top of the pyramid - It should probably be 5 - 10 cm wide and at least 10 - 20 cm long, but I haven't rigorously tested this. Maybe flat is best. I might call this the "roof".
Next the gold dust collection is carefully collected again and firmly pressed into one spot on a side of the pyramid. The best side would be upwind I think. At this point the construction is complete. It looks like a pile of rubbish with a lid on. It is easy to lose track of where you pressed the gold dust in.
The gold dust collection will form what is often called an "extender" for the coal that will shortly be added to it.
OK. Now go for it. Generate a coal. This could be - lighted charcoal nugget from a fire, lighted piece of charcloth, a coal from bow or hand drill etc. Make a dimple in your extender/ gold dust/ tiny bits collection and transfer your coal into that dimple. Gently firm it in if you can so it is half or 3/4 buried in the extender.
After that it is pretty well just blowing. But the clever bit is how little you must blow. Your extender is damp, and the rest of the tinder is damp. The flat surface below and the roof above might be damp. Only your coal is dry. So the coal has to do a lot of work - it first has to dry the layer around it before it can extend into it. Blow only hard enough to keep the coal alight at first, maybe for a minute or two. Gradually you will note the coal begin to grow. Keep up the gentle blowing, doing little more than keeping it going. At this early stage it is very delicate. If you stop blowing for perhaps more than 5 seconds the damp can beat you and put out the coal. Sometimes between breaths 3/4s of the extending coal goes out and your next breath does little more than relight the blackened areas.
It is quite common to begin to form a cave (where the material has burned away) with a thin layer of glowing material around it. If this happens just press in the sides so that the glowing parts come together again.
There comes a time when much of the material under the roof is glowing. Don't rush it, but carefully blow harder. When you think it is dry enough blow even harder - aiming for yellow/ white to replace the red. Between blows flames will start to appear, a bit reluctant and temporary at first but gaining in strength and persistance as you continue to blow and start feeding it kindling (tiny twigs). Phew, the job is done.
Try it. It makes a fantastic amount of smoke along the way that is really impressive!
The exploration that led me to this construction might interest some, that and the several other interesting (and perhaps novel) tinders that were spin offs. But that will have to be for another night.
Final comment. Some clever person might suggest that you might replace the single piece roof with a bundle of kindling (also damp perhaps), thereby being able to extend the fire directly into them. A very neat solution you might think. Yes, this is possible, but there are a couple of technical problems. The heat from below can burn through whatever you bound the bundle together with and it falls apart before its job of keeping the heat in is done. Secondly, the centre of the bundle is usually too dense to let the flames get into it so it can be reluctant to take a flame.
