Here is the current evolution of my PSK.
Originally I had one PSK, based on an "SAS" survival tin (an old pro-force tin). This is significantly larger in dimensions to an altoids tin, which I feel is generally too small for PSK use.
The lesson I learned with the old tin (many of the different configurations can be found by searching this forum) was that I wanted it to be a stand alone kit, capable of doing everything on it's own -- not only was there not enough room in the kit, but the thing was hefty and big. It really would only fit in a cargo pocket (where it would bounce against my leg and be uncomfortable) or in a belt pouch. No bueno!
Realistically, I will have at LEAST my EDC, so I thought it was prudent to alter my kit with an emphasis on supplementing the gear I knew I would have on me. Instead of a stand alone kit, I decided to make it part of a system. In that respect, this arrangement seems incomplete because the scope of the topic is PSKs.
The current setup includes two tins. The same width and length as the SAS tin, but shallower -- the same depth as an altoids tin. In this way, I can move them to my back pockets where they are more comfortable and ultimately I can actually carry more than I would have been able to by opting for a single tin. As a side effect, if I did opt to put them in my cargo pockets, now they're lighter and slightly less bulky so it's not as uncomfortable. That means I'll have it on me during hikes, and ultimately if you don't carry it it can't help!
That's not to say that tins are the ideal container, your mileage may vary of course as long as it fits in with your system. For me, I wanted crush resistance because some of these tins would have items that would not fare very well otherwise.
Knife and Bic Mini as a size reference
Primary Kit The size of my PSK is dictated by the desire to include not just minimal but a usable means to purify water, light fires, signal and create a shelter (since I can't include one in a package this small), and to be small enough that I'd carry it.
As such, I wanted to center the kit around whirl pack 1 liter bags instead of traditional ways to hold water like condoms or baby milk bags, and that kind of dictated the length of the tin. The white roll next to the purification tablets are two of these bags rolled tightly, with the paper on the outside to help protect them from abrasion. While I can't fit shelter inside this tin, I opted for a more robust pocket chainsaw which lies conveniently flat on the bottom so that I could at least have a reliable way to create shelter in my AO. The small matchbox contains misc little items that I don't want to lose including some safety pins, flies/lures/hooks, lengths of sparklers etc. The bobby pin can be attached to the flashlight to create a hat clip. Most of the other items are pretty self explanatory.
Supplementary kit This kit is full of stuff that would be nice to have for an unexpected overnighter (or even several days), including bug repellent and some minor medical stuff. I included additional fishing gear, and the two bags on the top left are 2x flies (woolley buggers) and below that, soft fish bait which take up little space. The hooks are circle hooks for unattended lines since they don't require a jerk to set them. I forgot to include simple bandages but have since added them.
I mentioned before this is part of a system. Typically on an outing I will also carry emergency shelter on my person; a disposable poncho, e-bivy and heatsheets blanket as well as bug headnet in a cargo pocket, and first aid items in my other cargo pocket. Combined with my EDC and these PSK tins, if I get separated from my bag for some reason I shouldn't be too bad off.
Realistically in my area (Tennessee) there isn't enough wilderness to get lost in for days unless I was injured. Typically if you pick a direction and move, you'll find civilization pretty quickly. Still, it's a fun thought exercise, and ultimately if you're willing to go through the effort to assemble your own kit, you're also more likely to have the knowledge and experience to take basic precautions so you're less likely to need it in the first place than the average person, so I feel it's not wasted effort.