Suggested Mods/"adjustments" to PFM40:
1) Carefully used hand pressure to slightly "adjust" fit of all components so they fit together properly and come apart easily. A bit of a fuss, but easily done--well worth the effort for hassle/frustration reduction. Not "normally" required with Swedish aluminum cook sets, unless they were damaged.
2) Pressed slightly "extending" hinge pin fully into the hinge using small "c" clamp. Filed burrs on ends of hinge and pin smooth with a small file.
3) (Optional) Bought a spare Swedish Aluminum "stove" along with Swedish military alcohol burner and Swedish plastic fuel bottle.
3) Used diamond cutting wheel on Dremel tool to cut a slot for cup handle into side of the Swedish stove opposite original cuts for pot ring and cup handle. See link to Blackie Thomas stove mods above. Cut is approx 5/8" vertical depth, and approx 2-1/8" horizontal width. This depth allows cup to seat on the internal supports within the Swedish stove, and the width of the cut allows cup to be installed/removed easily. Horizontal width kinda variable to suit the hinge on the cup but leave some slight additional horizontal width. Chamfer corners of top of cutout and use small round file to "round" the internal corners of the cut-out to eliminate sharp internal corners which are possible sources of heat/stress cracking.
4) (Optional) Will either sand or bead-blast external very "shiny" external surfaces and paint them with suitable high-temp black (exhaust header) paint. Such paint considerably speeds up cooking/heating times (compared to bare metal) and usually makes for easier removal of external soot/grime.
Observations:
1) Swedish stove has six (3 per side) additional vent holes around perimeter of its bottom. Will investigate/compare Swedish stove compared to OEM PFM40 stove using different fuel sources, including alcohol burner, fuel tabs, and trigs. Will take some time.
2) There is a nearly circular sliding "hook" on the Swedish and PFM40 stoves. Some say the main reason for this hook was for a squad cooking food with many cooking pots supported over a long fire pit on a pole to which the "hook" was secured. Maybe so. Some other clever folks have found that the "hook" can be used, in conjunction with the existing "tab" on the cooking pot to act as a reasonably decent pot handle. See Blackie Thomas vids.
3) As both the Swedish and PFM40 stoves are configured, it is not easy to use a low-profile, small gas burner inside the stove. It may be possible to drill a single hole suitable for the gas hose (and wider diameter gas hose fittings) in order to install a very low-profile gas burner within the stove. I suspect I'm not alone in wanting to experiment with this approach, since it adds versatility to these items without any significant drawbacks.
All for now. Learning as I go.
ETA: Am currently using 320 grit sandpaper to reduce typically "bright" Pathfinder stainless steel finish to a surface which can be painted, or even left alone with significantly reduced "shine". Will use flat black High-Temp exhaust header paint since common camo colors unavailable in that type of paint. Other folks have used less expensive "barbecue grill" flat black paint.
I found some 320 grit sandpaper suitable for my orbital HF Palm Sander, which should speed things up considerably, compared to hand sanding. No doubt some sheets of 320 grit sandpaper will be needed for specific areas.
Entire exterior of cook set will be painted, but leaving the "overlap" between top cup and bottom pot sanded, but clear of paint. Stove item will be painted inside and out.
Rounding-off all sharp corners/edges on stamped handle with a file prior to sanding for better paint adhesion/durability.
Painting over a properly prepared surface will provide decreased heating time of vessel and contents, as well as increased ability to remove grime, especially if wood is used as a heat source.
Ongoing project, learning as I go.
I understand that some of the measures I'm taking involve more effort than some will wish to take. To each his own.
ETA: Used RustOleum 2000 deg F exhaust header spray paint to coat external surfaces of the whole kit. NO paint inside any item, and no paint on interfacing surfaces between cup and pot. Spent most of the morning following directions on the paint can to progressively "cure" the paint in the oven.
Cured paint seems reasonably durable. Further tests required. May take some time.
Aluminum lid which will fit both the cup and pot (different dimensions) currently being made by UK vendor. See "woodlorien" on e-bay. Will spray paint exterior of well-sanded lid with common black paint, since it does not encounter much heat.
More later.