Introduction: The Mini Emergency Line Gun Project

Picture of The Mini Emergency Line Gun Project

Emergencies. They never advice. They catch you unprepared. And sometimes in some emergencies, we think "It would be good if someone had a gun like Batman's".

This project is for helping people in rescues: a home-made line gun capable of launching a flotable projectile to a man having problems in the water (Right now, In Colombia we have an winter emergency with storms, floods and avalanches, so I think this could be an useful idea for helping rescuers in his job). It could be useful to pass a line from one side to another, too. Or for grab the nearest tree or structure.

How it works? Like the weapon of an action figure. You insert the projectile, the spring compress, and the back part of the projectile gets caught in the trigger. When you press the trigger, the back part is released and the projectile is launched.

NOTE: because the position of the camera (and my bad aim), it looks like a short distance. But the steel cable is 9 meters (30 ft) long, enough for catch a tree branch if you are dragged by a river. (The next week I will do the experiment with a longest cable)

Without the steel cable, the projectile can fly about 20 meters (66 ft).

And why a spring? It's "easy" to recharge and you can do it over and over and over again. Air power could work, but if you want to recharge it, try to find an air compressor in a disaster area or in the middle of the forest. Gunpowder is another option, but imagine you are dragged by a river (powder and water are a bad combination) or inside of a burning building (powder and fire are a good combination, but very inconvenient, too).

This instructable is not the whole idea, but a concept. It's just the begining. is the home of the smartest minds of the world, and it would be great if this become an open project. Somebody carry on making a better spring launcher, and then another one improves the line system, and a third one implement a more resistant cord, and so on. Who knows? maybe one day every one of us could have a grappling gun in his emergency kit. Watch out, Batman!

Step 1: Disclaimers, Cautions and (because We Never Pay Enough Attention to the Warnings), Materials and Tools

Picture of Disclaimers, Cautions and (because We Never Pay Enough Attention to the Warnings), Materials and Tools
CAUTION: Because of the short time of the contest, this is a non tested prototype made of ordinary stuff. Instructables and M.C. Langer are not responsibles for injuries, death or property damage due to the bad, wrong or reckless use of this instructable. Make this project under your own risk. Don't use it in a real or simulated danger situation. Don't aim or shoot the gun against people or animals. Don't try to imitate movies, TV shows or comics actions like balancing your own weight, stop freefalls or fight criminals. Always use personal protection when you work with springs. In emergency situations, always call the competent authorities (911 in US and 123 in Colombia).


  • SUGRU (orange)
  • Hard spring (impeller)
  • Small spring (for the trigger)
  • 1 1/2" PVC Pipe (big enough for covering the hard spring)
  • PVC Cap
  • Garden hose pistol
  • Three 90° iron angles
  • Nuts and bolts
  • Empty yarn cone
  • Plastic bottle (It will be the head. I use one from a deodorant)
  • Aluminum cylinder (I use one from a discharged military flare)
  • 1/2" PVC pipe and cap (Note: it will be great if this is replaced with aluminum pipe, or another light metal)
  • Thin steel cable.

Cord: I use thin steel cable. Paracord could be useful. I know in US you can find a better and lighter cord.

Tools and others:
  • Dremel rotary tool
  • screwdrivers
  • pliers
  • paint
  • superglue
And remember the rules:

1. If you don't have it, replace it!
2. Use protective equipment (dust mask and goggles)
3. Beware of drilled and soldered hot surfaces
4. Work in a good ventilated area.
5. Always have junk in stock
6. Enjoy!

Step 2: The Trigger

Picture of The Trigger

The trigger is easy. Cut an iron angle and insert a screw with a plastic piece (for activating the gun with your finger). Then, insert the small spring, and fasten with a nut.

Step 3: The Launcher

Picture of The Launcher

Take the PVC cap and make a hole in the middle, big enough for the PVC (or aluminum) pipe of the projectile. The pipe must go loose across the hole. Then screw the trigger to the cap. It has to be mobile. Couple the big PVC pipe into the cap, introduce the big spring and fasten the spring base, the cap and the PVC pipe with screws. Fix the end of the small spring to the cap, so you can press the trigger and it will return.

Step 4: The Handle

Picture of The Handle

Disarm the garden hose pistol. We will need the handle. Adapt the yarn cone. Then, use the iron angles and a metal strip to strip the handle to the launcher.

Step 5: The Projectile

Picture of The Projectile

Take the aluminum case and attach in the center of the bottom the 1/2" PVC cap. Drill another hole on the bottom, insert the steel cable and fasten it inside the case. Insert the other end of the cable into the PVC pipe, and drive te cable to the gun. If you want, just use a piece of cable in the projectile, and made a loop for attach another kind of rope or stuff to the projectile.

Fix the PVC pipe to the cap using screws. Make a small cut in the middle of the pipe. When you charge the gun, the trigger will enter into the cut, keeping the projectile ready to launch.

Adjust the plastic bottle into the aluminum case. Because the primary objective of this gun is for acuatic rescue, the projectile must be watertight. Use SUGRU for sealing the holes and spaces between case and bottle. Adjust and fix using screws. I painted orange the projectile because highlights.

Step 6: Sugru, Painting and Charging

Picture of Sugru, Painting and Charging

If you want, paint the gun. I use SUGRU because I wanted a more ergonomic (and colorful) handle.

For charging the launcher, introduce the projectile into the launcher and... use ALL your force!


BU1LD45TR4L00 (author)2017-03-05

Where do you get the hard spring(impeller)?

In a junkyard.

deswiger (author)2016-07-23

I needed this months ago. Doesn't anyone read minds any more?

Good job, thanks for the share. Semper Fi

M.C. Langer (author)deswiger2016-08-11

Thanks deswiger!

skulljo (author)2015-04-03

Can it rewind itself

laffinm (author)2014-05-25

You should make a shooting video

rncbme (author)2010-12-16

I've used something similar for years. I zip-tied a spinning reel to the underside
of a slingshot and put a small weight on the end of the line. For me, its primary function is shooting the line over trees and then pulling antenna wire back for HAM Radio use; Works like a champ. I always use the slingshots that have surgical tubing for the kinetic energy... While it's only good for 50-75 yards, it is consistently accurate. I use fifty pound mono-filament line.


Highvoltage89 (author)rncbme2014-03-17

hey what is your call sign mine is KG5AOD

M.C. Langer (author)rncbme2010-12-16

I have fity pound nylon monofilament. But a very thin line has a problem: could cut easier the rescuer hands. I want to use the monofilamente for a speargun like the one in Batman Returns.

Advar (author)2013-08-26

Simply awsome. Nice job! :)

M.C. Langer (author)Advar2013-08-26

Thanks Advar!

MU5ICI4N (author)2013-05-30

Amazing! What a sleek, wonderful creation. It would be interesting to have an adaptable projectile with different heads that could click in, such as a grappling hook, buoy, foam-tipped, or one with a little compartment (for getting emergancy supplies to hard- to reach areas).

M.C. Langer (author)MU5ICI4N2013-05-30

Thanks a lot MU5ICI4N!! :-)

fretted (author)2012-10-29

Use Para-cord and a monkey fist ?

Wyattr55123 (author)2012-08-08

try heavy fishing line, not steel

HBDWMA (author)2011-03-12

heavy line would mean a bit less distance tho, of course.

HBDWMA (author)2011-03-12

Just a thought: You can duct tape a fishing reel to the front of a slingshot (wrist-rocket type, not the "Big Y" tree branch type) and launch lines 100 yds.

rimpest (author)2011-02-05

Eres Español o que?

M.C. Langer (author)rimpest2011-02-05

Soy Colombiano! De Bogotá! :-)

jmonty (author)2011-01-31

i gotta say M.C. Langer, this is a pretty sweet idea! probably will save a few lives dude!

M.C. Langer (author)jmonty2011-01-31

Thanks Jmonty!! :-)

gbearpdm (author)2010-12-28

I can iamgine this with a spray propellent/ignition system like they use on potato guns, but I'm not smart enough to design it.

spenfisher12 (author)2010-12-24

may i reccomend 550 paracord in place of steel cable

Foaly7 (author)2010-12-23

Is airplane wire too thick for this?

M.C. Langer (author)Foaly72010-12-23

I guess.

MaClay (author)2010-12-16

Nice piece of engineering and application of reusable and repurposed materials. And in the vein of your request for comments from the instructable community, may I suggest the use of an eye splice in your cable instead of the much heavier cable clamps. A splice although not legally rated for supporting a load, it was used for a long time before compression sleeves and the like were developed. Also the eye splice being lighter would increase range and be less likely to snag on itself or other things (Batman's cape). You could put a copper sleeve over the barbed ends and solder in place, so you wouldn't have to get it perfect on the first try. Plenty of www info to help you do it. A lighter synthetic line would be best, but you are using what you have access to.  Once again, well done, and keep up the good work

M.C. Langer (author)MaClay2010-12-17

Thank you very much MaClay!!! It's a great suggestion!! :-)

billhorvath (author)2010-12-16

This is impressive, and smart! As a former wilderness EMT, I can think of any number of uses for this, both rescue-related and otherwise (E.g., it'd make for an easy way to hang a bear bag.) Great work!

M.C. Langer (author)billhorvath2010-12-17

Thank you Doxsys!!!! :-)

RayKenn (author)2010-12-16

Excellent work! With a little "polishing" I could see a definite market for this in a variety of areas.

M.C. Langer (author)RayKenn2010-12-17

Thanks Raykenn!!!

dropkick (author)2010-12-16

Parachute cord (sometimes called 550 or para cord) would be much lighter, would fly further, and most importantly is rated for supporting much greater weights than the thin steel aircraft cable.

The 3/8" steel cable is only rated to support 30 lbs. while the para cord is rated for 550 lbs.

People often make this mistake, thinking the steel would stronger.

I use the thin steel cable for supporting a bear bag when I'm in an area where I've been told I have to worry about rodents (or occasionally bag smart bears) chewing through the supporting cord. Other than that I don't use it for much of anything.

M.C. Langer (author)dropkick2010-12-17

Thanks for the advice. I will make some experiments with paracord.

mathieulj (author)2010-12-17

Very nice idea indeed, although i must caution those who think this is ready for the prime time. In this form, you are still firing a metal projectile. NEVER, EVER fire it at/towards someone as you could make the situation worse(by ex. hitting them over the head). If you are in a situation with dire need and have only this first version to help, fire it ether way over the person (the line will drop to them with less of a thud than the aluminium projectile), or in front of them so the current brings the to the line.

This being said, I am a fan of the concept and will most likely make my own version in the distant future (with some sort of soft projectile).

M.C. Langer (author)mathieulj2010-12-17

Thanks Mathieulj. You have a point: if you don't use this concept properly, you could be killing someone instead of saving him.

Thaikarl (author)2010-12-16

this is wonderful. an inspiring start. i'm a sailor, and i have thought about something like this for an overboard person. i'm imagining a similar device, that was all built inside a PVC tube. the tube would have a looped strap on the bottom end for a grab handle. the pvc would have a inner and outer, slip fit tube. to cock the mechanism, you would slide the outer tube to the strap end, engaging a simple trigger latch that would pop out of the side of the tube when it was engaged. press the trigger and the weighted, projectile would shoot out the end of the tube. in an open water situation, you would have a conflict between weight of projectile - so it would fly, and lightness- so it would float where a person could grab it.

in a tense, emergency situation, throwing accuracy can be very bad, and you might not have a second chance. the antennae throwing devices in those video's are bulky, complicated, and expensive. great for antennae's, poor for a flood or overboard victim. you are aiming for something a person can make, easily accessible and inexpensive. super! i'll have to think about this one some more.

M.C. Langer (author)Thaikarl2010-12-17

Thanks Thaikarl!!!! Well, I was from the Colombian Navy!! :-)

And you're absolutely right. About all.

steveastrouk (author)2010-12-16

You know, I look at your line launcher, and I think of all those porr folks who drowned off Christmas island yesterday who might have been saved if there had been a way to get lines to them.

Kudos, someone might make one and save a life


M.C. Langer (author)steveastrouk2010-12-16

Thanks Steve!! And that's the idea. I don't want to see this like MY project, but OUR project. Making a good Line Gun between all could save a lot of lives!

greaserjoe (author)2010-12-16

what if you added a CO2 can and instead of the yellow rocket,you add a fiber glass hook??

M.C. Langer (author)greaserjoe2010-12-16

Could be!

lemminggenocide (author)2010-12-12

replace the spring launcher with a pneumatic system otherwise it will stay horribly weak. No point using a launching system for something you could do with your hand

What if you are a rescuer in the middle of a river and you don't have enough force in your hand for throwing a line? If you have a line gun, you could launch a cable to the nearest rescuer or to a branch. Having a steady position for launching a line is anything you don't have in many emergencies, and a spring powered gun could work.

You have a point with the hand thing. But, as I said, this is an iniciative, an open project. It will be good to see how you make the grappling gun with a pneumatic system.

mman1506 (author)M.C. Langer2010-12-12

you could use interchangable co2 canisters and attach the onto the side of the gun

M.C. Langer (author)mman15062010-12-13

Not a bad idea!

Procrasticus (author)M.C. Langer2010-12-16

A brilliant idea! By the way, I like your wire gun here very much. It's nice to see someone trying to make something with more potential use than fancy home decorations, hahah.

M.C. Langer (author)Procrasticus2010-12-16

Thank you Procrasticus!!!! :-)

lol it was just a suggestion, I don't really have an interest in this and I doubt that anyone will go any further than making reccomendations, but hey I'm a cynical jerk. The throwing thing wasn't an insult just a bad analogy. here are examples of pneumatic launchers made for a similar application, but with far greater power. They also use fishing reels which might be a good idea for your launcher.
oh also I'm fairly sure someone fit enough to become a "rescuer" would easily throw that distance whilst treading water :P

Your videos are great! But they still have a problem: the cord. We need to launch a cord (or line) capable of carry the weight of, at least, one person.

I know it wasn't an insult, and you're absolutely right about all you said. And the idea here is to make improvementes to this project. And... c'mon! The Sugru Life Hack is a very speed contest. I made this in one day. Now, without the presion of the closing date, I can make a better one (but with springs. I love springs!! ;-)

About This Instructable




Bio: I'm Mario Caicedo Langer, from Colombia, former Navy officer and BSc in Naval Sciences. Right now I'm Technical Director and Technology Lead Teacher ... More »
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