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They're great for carrying jumbles of electronics through airport security xray machines and capsized boats.
The rubber is limp, quiet, and doesn't develop pinhole leaks as much as stiffer materials.
It's quick to look through the side of the bag and see what exactly is in it.
I prefer them to a bulkier laptop case. If I want more padding I wrap a shirt around it.

I made these two bags for a trip to Indonesia a few years ago and have been carrying them ever since. The original plan was to protect my computer and electronics from moisture and humidity. To seal the bags up I rolled the ends up and tied them with a strip of the same rubber they're made of. I brought a kilo of reusable desiccant with me. The wet side of the big volcano in Bali was especially humid. It felt like it was raining off my eyebrows most of the time. I didn't end up spending too much time in super-humid areas and gave my desiccant to people who did.

None of my gear died on that trip, and from there I went on an outrigger canoe sailing trip in New Zealand. These bags were great dry bags for camping gear and food.

Now I carry them with me all the time. I don't bother sealing them, I just fold the ends over unless I expect boat troubles. One bag has my laptop in it and the other has my misc electronics.
I mislaid one of them recently and missed it a lot.

This project is pretty simple, but you can't buy bags like these and they're really nice to have.

Step 1: Cut, Fold, and Weld the Rubber Sheet

I used 12 mil clear urethane rubber sheet from API inc. A friend bought the material for kitesurfing bladders, but it turned out to be way too heavy for that. If you don't mind PVC you could use your grandma's couch cover, or a clear shower curtain. Urethane is better than vinyl because it's more flexible and maybe less toxic to the planet. Polyethylene is too stiff, cloudy, and prone to fatigue. Don't use it.
Seattle Fabrics sells lots of coated fabrics that would work for this, and they specify which ones can be welded.

Some types of material will need to be washed with soap before you can weld them.
Cut a rectangular piece big enough to make the bag you want.
Fold it over and weld the edge with a hot iron.
Keep it from sticking to the iron by putting a piece of kapton (high temp plastic sheet) or tinfoil over and under it. Experiment with scrap material til you get the iron to the right temperature and get the knack of it. Rub the kapton on your nose to make it greasy and keep it from sticking.
Put a narrow stick under the edge you are welding on to keep from welding too far into the bag, and so you can put more pressure on the edge.

This is the same process (and picture) from Make Your Own Waterproof Camera Enclosure
Sorry to be a spoilsport, but as a chemist, I worry about people melting polyurethane. Upon heating, the carbamate linkages can decompose into isocyanates (the compounds from which they're made), which are one of the leading culprits of occupational asthma. Thermal decomposition of urethanes can also generate other nasty things like hydrogen cyanide. It's a cool project, but the worrywart in me compelled me to give you a heads up!
i have a question...Why all this trouble to make a bag????why dont u just use ziploc???
because this way the terroists can sneak the bomb on UNDETECTED
The material inside the bag is not detected?
you can sneak a small knife through a metal detacter by wrapping a lot of electrical tape on it.
thats bull. the only way to pass a without it looking like a knife in the x ray, and metal detectors is by camoflageing it, putting tape on it will not help in any way, shape or form.
how do you think they smuggle weapons into prisons? they wrap it in tape, and kiester is. sometimes they'll have females stick it up their vaginas.
like i said, wrapping it in tape will do nothing, they have metal detectors in prisons. they make the weapons once theyre in the prison, they dont take them in. if they do, they bribe the guards.
well. idk. i saw it on a movie.
if you see something in a movie, please dont just say it like "ya, im sure and i am ready to bet on it", do a little reasherch on the subject first.
actually, I remember now... I saw it on the History Channel on a show about the Aryan Brotherhood.
I saw that. That was using Charles Manson's groupies though.
If we got sigs, your idiocy would be sigged.
lol this is why instructables is blocked at my school. -_- it says that this is a terrorits/militant group or something ahhaha :-)
lol my school says its pornography
XD How far off!
ya we even had things blocked as educational
XD Yes that Is very Annoying
Go to kproxy.com to unlock it!
xproxy is blocked >_<
If you have a relative that does scrapbooking, sewing or quilting, they likely have a teflon sheet and a miniature iron that can do the same job as the big one with a lot less hassle. (and for free) I use a teflon sheet for the same things as you use a kapton sheet (minus the nose-greasing), so I presume that it would be okay to use for making bags.
hi i wondered how much you paid for the plastic and if any one in the UK knows of somewhere to get the stuff
what kind of roll did you get. I can't fine it on API's site.
Unfortunately I can't find the little card that came with the roll. I measure the thickness at 14 thousandths of an inch(mils) thick. That seems thick. I thought it was thinner, 12 mils. Maybe my micrometer got dropped. Maybe the stuff is "thermoplastic urethane".
An alternative way of sealing this stuff up is vinyl glue<br/><a href="https://www.instructables.com/id/EWHO8U8064EP286D8P/">https://www.instructables.com/id/EWHO8U8064EP286D8P/</a><br/>
Nice project! I've used regular PVC pipe cement/solvent to patch air mattresses and inflatable boats when that was all I could get. I cut a patch from a showercurtain if there wasn't any extra hanging off a corner. The glue to look for stays a bit chewy when dry. One thing to watch out for is that urethane will not stay welded or glued to PVC even though they can look and feel the same. I had a painful learning experience with this with some flotation airbags that I had bet my life on.
My tumors really dislike the taste of chewy vinyl glue (o;
"They're great for carrying jumbles of electronics through airport security xray machines." a homemeade rubber bag with a laptop inside... can anyone say.. cavity search?
Really, the securazoids love these things. They can paw over the bag without dumping it out. I haven't been "randomly" selected for extra searching in a long time. Sandals are good airport timesavers also.

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Bio: Tim Anderson is the author of the "Heirloom Technology" column in Make Magazine. He is co-founder of www.zcorp.com, manufacturers of "3D Printer" output ... More »
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