Sean and John,
Thanks, happy to share. I got the idea a couple of years ago when I was trying to get the 11 fl oz SP Solo Cup to work with a Sea to Summit X-Mug (where the X-Mug serves as the travel lid). I needed a lid to fit inside, and the lid in the photo was born. The weight of the kit with the X-Mug was too heavy (the X-Mug weighs 2.4 oz., the Fosters mug weighs 0.8, I believe). Plus, boiling 16 oz. was kind of a drag... :-)
Another plus is you can rotate two of the panels slightly to create a slit: perfect if you want to place a temperature probe when doing dozens of stove tests.
I forgot to mention the windscreen, and yes, that fits inside with all the rest, but since it steps on Trail Designs toes a bit, I'm keeping that design private for now (it works like a cone, but fits neatly inside the pot without any fuss).
Getting the lid to fit the diameter of the pot lip is easy (trace with a finepoint Sharpie), but getting it to drop below the lip (thus the inside diameter) is a bit trickier, mainly because most pots aren't perfectly round. The SP Bowl is supposed to have a drop-lid, but at that diameter and with the thin material, it kind of wobbles a bit. If there's a way, I'll post a PDF of the templates under my profile so everyone can print, paste, and cut. Have to find them first...
Keep in mind these lids aren't completely airtight, and shouldn't the be used for straining pasta as their too flimsy.