Very cool trap indeed! In the field, however, all you need to do is to cut the top off and bury the bottle with the bite into the ground vertically to the rim. Small critters cannot climb back up the smooth wall.

For the string procurement I'd prefer this "device":



But I'm always having some screws/nuts/washers and wood screws as well in my kits - too versatile not to.

Club soda addiction here. Cold, fizzy, and doesn't dissolve my enamel like regular colas.

On the subject of both 2 liter bottles and morale: 2 liter bottles are rated between 50 and 100 psi. I suggest water bottle rockets and alcohol vapor rockets (OK, more of a soda bottle mortar). I know it's childish, but for off-grid / grid-down family fun, it beats trying to teach the kids to play poker.

https://youtu.be/0qzOzjRJpaU
https://youtu.be/wuz0curb_hg

Making string from PET is interesting. What is the tensile strength of a typical (4mm or so) strand?

Probably not a good way to acquire a dynamic climbing rope - but for other uses....

It's polyester, which I found measured around 138 MPa for the thin film: http://www.shimadzu.com/an/industry/petrochemicalchemical/i206.html
That's the same as for cast iron, or bone.

Quite strong if made without nicks (takes practice). Most importantly it's hot-shrinkable. So you can make very tight joints with it (i.e. for the shelter building). See some proof (and another DIY tool guide) here (in Russian, but you can just turn off the sound for clarity, oh, he's made English subtitles already):


and here

Very interesting and potentially useful. But I do have a very elementary question - just what is an MPa? i rather imagine 138 MPa is stronger than 20 MPa, but probably not as good as 50,000 MPa. Cast iron and bone are not what I think of as having particularly notable tensile strength (at least the old bones with which I deal).

Heat shrinking sounds interesting. I wonder how many strands of this cordage I would need to plait together in order to get a rope that would meet UIAA specs?

Or this variety - the self resetting mouse trap:

It's all here: https://en.wikipedia.org/wiki/Pascal_(unit)

For the UIAA specs rope, I think, just get it's TS, divide by the 138, multiply by the cut surface of the sample tested above divided by your bottle strand's cut surface, and then multiply by 2 the resulting number of strands required just in case Should be a safe estimate, as you most likely will intertwine all the bands which makes the total TS better.

It's based on the Pascal -- a unit measuring force on a defined area, the equivalent of pounds per square inch (psi). In wasn't aware it was used to measure tensile strength, but upon reflection it makes sense. https://en.wikipedia.org/wiki/Ultimate_tensile_strength



+1. How much does it shrink? The stuff is everywhere. Contemplating the possible field uses now (cue sound of gears whirring and clanking in Babbage difference engine). Processing, processing ...

Not much f.w.i.w., but watch the second video, it shows exactly what you want - tools handles wrapping, looks promising. So far I used it just a couple of times to secure my DIY wet paper press ends - works as a disposable clamp better than paracord.

I've used those, based on a hint from this forum. They work. The plastic bottle seems more efficient than the beer can I used. In freezing climates, an inch or two of used motor oil at the bottom dispatches them quickly, and there is no smell. But live catch is also possible. I'm happy to report that I've never been that hungry.