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Learn how to make a simple coilgun using only a few parts that are fairly easy to obtain. Be Willing to spend more than a week on this and you might need a few heavy power tools (Only to make good projectiles). I built my first one in only a week after I had all the parts.

Coilgun Principal:
Coilguns(Pulse Accelerators), like railguns(Linear Accelerators), use intense electromagnetic fields to propel objects at incredible velocities unreachable with modern gas driven weaponry (given enough stored energy of course). This coil gun is known as a reluctance coil gun. The coil uses its electromagnetic field to pull a ferromagnetic (magnetically affected) projectile, in this case a shaped steel round, toward its center. Ideally the current supporting the electromagnetic field will turn off when the projectile is in the center allowing the projectile to continue traveling down the barrel, out the gun, and to the target. Use a coil and a few batteries to understand the properties of this system better. Many coilguns incorporate multiple stages at lower energy levels as efficiency tends to die off as more Stored Energy is used for a single coil design. For more information go to step 5.

A basic coilgun operation diagram is included at the bottom.

'!!!!!!Learn More About Coilguns!!!!!!'

What is a relay?? (Elaboration on step 2)

How does it work?
A relay is a simple electromagnetic switch. It uses an electromagnet to pull two contacts of a separate circuit together, completing the circuit and allowing electricity to flow.

What is it used for?
A relay was originally used to allow a machine or computer to switch something on or off electronically. In this application it is used to switch the capacitors energy into the coil.

Why use it?
Relays allow more current to pass through them than regular push button switches, which normally weld together. You can use a very high rated toggle switch for this, but it is usually more expensive and larger than a relay of the same rating.

Part Deals

The Parts You Need Are:

From Radio Shack or Other Electronic Parts Dealer:
-20 or 22 AWG Hookup Wire (Buy both the solid and stranded)(Larger wire is better because it lowers the resistance in the system which increases the coil gun's efficiency)
-22-20 gauge Magnetic Wire (Depending on your coil preference;See step 2)(Radio Shack has a Package with 40 ft of this but I recommend buying it from a different store to save cost and to get at least 100 ft for a coil more than 7 layers thick)
-A Relay (Electronic Switch), Preferably 30 Amps or more (I got a 12VDC/30A SPST Automotive Relay from Radio Shack, but I would recommend a higher voltage and current rating)
-A Momentary Switch( I used the SPDT Switch with 3/4" Roller Lever from Radio Shack, but you can use a lower rated switch)
-An On/Off Switch(I used the DPDT Heavy-Duty Rocker Switch from Radio Shack but you can use a lower rated switch)
-Battery Packs (More than 2 2AA Holders and 1 9V Holder)(The more 2AA Battery Packs the better)( I would suggest getting a few 2 C Battery Holders as they provide substantially more power to the Charger, resulting in a MUCH faster charge time; be careful not to over load your chargers, see last step for safe charger to battery ratios.

From Other Places:
-Used Disposable Camera's (The More The Better as this is the gun's central component), You can get them by asking most photo places like in Walmart or CVS for used disposable camera's. Remember: it is for the batteries, not a gun...never
-Straws from Burger king or local chain(You May use another place's straws but the coil's inner diameter will differ; Of course if you choose a smaller straw a smaller projectile will go faster but not pack as big a punch, AKA momentum)Also,Smaller Straws may be used to place on the back of your projetile for stabilization, this works well.
-Large Nails (3/16 to 1/4 inch Diameter, or bring your straw to Home Depot to fit the right nail)
-A Bolt, two washers, and a nut. (The bolt needs to be the diameter of your straw and the washer needs to fit well and be as wide in diameter as possible)
-A spray paint "can gun" handle or other handle. (I got mine from Harbor Freight)
-Plexiglas, wood, or sheet metal(Optional for gun casing)
-Electrical Tape
-Solder
-Flux (Not necessary, but it does help)
-Super Glue/ Epoxy/ Hot Glue(Used for gun casing)

Tools
-Solderer
-Pliers
-Wire Cutters
-Wire Stripper( A big help)
-Scissors
-Glue Gun( For outer casing)
-Screw Driver(Flat Head)( To get cameras apart and discharge capacitors)

Losing Drive To Build This? Check out The Videos

The PAR-1 video demonstrates the kinetic output of a 12 layer coil with a 470uF 400V(to 450V) capacitor, that's only 50 Joules!.

My Web Page: Future Experimental Systems
Go to see some coilgun and railgun projects of mine.

Finished a coilgun and want to share it? Post it Here: Coilgun Arsenal

Useful Electronic Goods Sites:
- Mouser Probably the best Distributor I've come across, vast selection of items, best pricing for a non-wholesale electronics site, and great navigation and organization.
- Goldmine Great prices on useful parts
- Digikey Good for hard to find parts.
- MPJA Great place to buy magnetic wire and LEDs
- Electrostore Large high voltage capacitors at cheap price and other high power components.
- Surplus of Nebraska Great prices on magnetic wire if bought in large quantities.
- Alltronics An OK surplus store
 
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Step 1: Charger Circuits

The first Step is to dispose of the disposables. Take apart the Kodak cameras first by using a screw driver to pry the case open on the side. Remove all but the center plastic part that holds the circuit board (BE CAREFUL, OR don't either way you will probably shock yourself unless you wear gloves, a good idea for the weak of heart(literally)) Make sure the battery is out then touch the capacitor's leads together with a screwdriver to discharge it, the capacitor is the cylindrical device that has two leads extruding from it, location shown is second picture.

Why connect chargers into a bank?

chargers themselves aren't very powerful, but when you connect them together in parallel like shown in the last picture you increase the possible power output that the chargers can handle. Increasing the number and size of your battery bank (at 3V) will increase the chargers output (to a point) until the chargers fry.

Connecting the chargers in Parallel OR Series?

The chargers are connected in parallel, i.e. each terminal is connected to the same terminal on the adjacent charger as shown in the picture diagram. I do not recommend putting the chargers in series, so don't worry about it.

Look and read the picture comments, the pictures show you how to make your chargers better than I can describe it.

First take your circuit and use a pair of wire clippers and cut off the section defined by the small transformer on the top right of the circuit (this includes a transistor and diode)(look at the picture for reference). Attach leads as defined in the picture.

Camera circuits are mostly inefficient i.e. 16% by my testing, if you want your gun to charge faster and with less battery drain check out my DC to DC HV Boost Converter.

The Mini Charger Idea credit Comes from Instructable member "245Tommy" who got it from you tube member "Halo2maniaccc". Thank You both

TEST EACH CHARGER INDIVIDUALLY BEFORE YOU PUT THEM INTO A BANK, some may be defective.

Remember: Flux/Rosin (Which is used to enhance solder's "stick") is important here. You do not need it, but it does help a lot.

Step 2: General Details

Capacitors:
Connect the capacitors Via bare Solid wire and solder (Line up the negative with the negative!).
The capacitors should be rated 300 VDC to 900 VDC for best results.

The energy found in a capacitor can be calculated based on this formula:

1/2 x C x 1e-6 x V2

or

0.000005 x C x V x V

Where C is the capacitance in micro-farads (uF) and V is the Voltage the capacitor is charged to in Volts.

Coil:

Here is a good video that shows you how to wind your coil:
How to Wind a Coil

-Bolt of an appropriate length and diameter
-Large diameter washers and nut to fit on the Bolt
-Electrical (usually black) tape or preferably super glue or epoxy
-Straw or paper to create a space between coil winding and the bolt
-Magnetic or Enamel wire
-I use Plexiglas washers created via a hole saw and drill press. This allows you to super glue each layer to the plastic washers that way the coil is more structurally sound when taken off the coil. If you choose to have plastic washer you can feed the starting wire through a grove or hole cut in back plastic washer, this aids greatly in winding.

    Now, get your straw or piece of paper and cut it about 1-2 mm longer than the desired length of your coil. Put the end washer(s) on the bolt and place the straw or paper on the bolt as shown in the picture, if the straw doesn't fit on the bolt simply cut it length wise.fit the remaining washer and nut on the bolt as shown.

    Feed the end of your magnetic wire though the center of your end washer and allow about 2-3 in of the wire to come out the other side. Wrap the wire that was put through the end bolt around the head of the bolt to secure it in place. Now start to wind the coil in a clockwise or counter-clockwise manner around the bolt. DO NOT switch from counter-clockwise to clockwise or vise versa, always wind in one direction around the bolt, otherwise your coil will not work. Continue to wind until you have reached the other end, secure the wire with your thumb and if you have tape tap the layer down tightly, if you are using super glue DO NOT glue the first layer, this will glue the wire to the straw or paper.
To make a second layer simply continue to wind, rotating in the same direction you started and making you way back to the other end of the coil on top of the first layer. Once you have reached the other side glue or tape the assembly and continue to wind in the same clockwise or counter-clockwise direction back and forth along the length of the coil. Wind the coil as perfectly as humanly possible and keep the wire as perpendicular to the bolt as possible.

Once you are done with your coil tape or glue the assembly as tight as possible and let it sit for few hours. Then, take the coil off the winder as carefully as possible and remove the inside of the straw or paper with pliers.

To Make the Guns grip open the plastic handle and hot glue in the roller switch so that the switch is triggered by, well, the trigger. Drill holes in the back and attach wires to the switch (1,3) and then put the wires through the holes. Close the Handle and if you can hear a click when you pull the trigger it should work.

RELAY
A relay has two working elements in it, an electromagnet and a mobile contact.

First a little Vocabulary:
-  NC-Normally Closed-When no current is applied to the electromagnet C and NC are connected
-  NO-Normally Open-When current is applied to the electromagnet C and NO are connected
-  C-Common- Connected to either NC or NO based on state of electromagnet
-  SPST- Single Pole Single Throw- Either NC or NO is included in this relay, not both

       This relay will have 4 connections, Although some appear to have more, If the location of the electromagnet is unknown apply a 9V-12V source to each connection combination possible until a click is heard, this is the electromagnetic and when the relay is hooked up as in the diagram in the subsequent step the gun will fire when a proper voltage is applied to these connections again.

-  SPDT- Single Pole Double Throw- Both NC and NO are included in this relay(Shown in Picture below)

    This relay will have 5 connections, Again If the location of the electromagnet is unknown apply a 9V-12V source to each connection combination possible until a click is heard, this is the electromagnet and when the relay is hooked up as in the diagram in the subsequent step the gun will fire when a proper voltage is applied to these connections once more.

For this Project either a SPST or SPDT Relay can be used, we only use the C and NO connections so a SPDT will have an unconnected Lead.

Opening the Relay will allow you to find these connections more quickly, but put the cover back on when your ready to install the relay.

Also Below is a picture of the semiautomatic configuration.

Step 3: Coils, Capacitors, and Results

Picture of Coils, Capacitors, and Results
Coils, Capacitors, and Results
All measurement are taken from velocity test with chronograph and are maximum achieved.

22 gauge:
-UM:7 Layer, 33mm L, 6.5mm InDia 1320uF 330V E.37m/s 4g(11*330V 120uF)
-8 Layer, 30mm L, 8mm InDia 960uF 350V 24m/s 8g(8*330V 120uF) 3.9%
-12 Layer, 30mm L, 8mm InDia 600uF 350V 12m/s 8g(5*330V 120uF) 1.57%
-12 Layer, 30mm L, 8mm InDia 470uF 450V 27m/s 8g(1*400V 470uF) 6.1%
-16 Layer, 30mm L, 8mm InDia 470uF 450V 28m/s 8g(1*400V 470uF) ****Best results 6.6%
-UM:12 Layer, 30mm L, 8mm InDia 470uF 800V E.>50m/s 8g(4*400V 470uF)

20 gauge:
-UM:12 Layer, 29mm L, 8mm InDia 940uF 400V 31m/s 8g(2*400V 470uf)
-UM:12 Layer, 12mm L, 8mm InDia 1200uF 350V 26m/s 8g(10*330V 120uf)
-8 Layer, 12mm L, 8mm InDia 880uF 450V 13m/s 9.0g(4*400V 220uF)
-Ferrite Surrounded-8 Layer, 12mm L, 8mm InDia 880uF 450V 14m/s 9.0g(4*400V 220uF)
-8 Layer, 30mm L, 8mm InDia 1100uF 450V 33.0m/s 9.0g(5*400V 220uF) SCR Switched 4.4%

E.=Estimated Velocity-The velocity here is estimated based on visual comparison to the other results, they are Not measured.
UM=Unmaximized- Coil not experimented with to achieve maximum results

If you do not have access to a chronograph the method HERE is relatively accurate.
If you use this method to get velocity results make sure your coil is perfectly horizontal and don't fire to the ground, fire at a piece of foam that is a meter or so away.

Also HERE is an optical velocity measurement set up.

Even at best the shown results are + or - 20% correct, this is because most electrolytic capacitors capacitance rating is within the + or - 20% region.

Step 4: Bring It All Together

Picture of Bring It All Together
Picture Diagram Basic Coilgun.bmp
Schematic Basic Coilgun SCR.jpg
Now Connect Everything Together. Follow the Picture Diagram and Schematic.

Test the system, if it works use Plexiglas, wood, or even metal to make housing for your gun depending on the desired size/weight etc.

The Battery Banks Must not exceed +3V for relatively safe operation.

Step 5: Projectiles

Picture of Projectiles
100_1272.JPG
100_1282.JPG
100_1285.JPG
Projectile Material:

The projectile material is a very important part of your coilgun system.
-Basically your projectile must be ferromagnetic, i.e contain mostly Iron.
-It must be magnetically soft, which means that if a magnetic field is applied to it the material will not stay magnetized.
-It must have the highest magnetic saturation point possible

The Best Materials I know of are listed below from best down:

Nickle-Cobalt
Nickle-Iron
Pure Iron
Low Carbon Steel (Steel with a rating of 10XX where XX is the lowest number possible, such as 1006)
Stainless Steel - Most stainless steal is NOT ferromagnetic, it must contain at least 80% Iron to be considered ferromagnetic.

Round Low Carbon Steel 1006 from McMaster-Carr will be the best material I found for your projectiles for a reasonable cost and availability. It is the lowest carbon steel I could find for "low quantity" purchasing.

If you want efficiency in your coilgun but don't have the tools, time, or effort to make your own projectiles buy HERE, you can customize your rod cuts for a relatively low price and you don't have to do the tedious work, and the steel is low carbon, which means higher iron content and more efficiency. Also they sell acrylic for my casings, which is a plus.

Projectile Fabrication

Now this is the "Hardest" and most time consuming part. In order to make the projectiles, cut the heads off of the nails using a Dremel tool with a reinforced cutting disc (will wear quickly) or a large grinder with a cutting blade.
You can also use a hacksaw with a steel cutting blade, credit for this idea goes to member jondo huang, I never even thought of it. This is the preferred method as it is cheaper and the cut is much better.

Then cut the rest of the nail to the correct length ( They should be 3/4 to 5/4 the length of the coil). If you are looking for efficiency, i.e. velocity, simply grind the edges of the projectile to a rounded flat surface and not pointed.
Mine are sharp so they can do more damage. In order to do this I placed the projectiles in a drill press and used the grinder to grind the edges down, if you use the Dremel you can get a smoother finish and finer point. This can be a long process, but well worth it.

You can glue smaller diameter straws to the end of the rounds to stabilize them, usually the longer the round, the longer the stabilizer will have to be to ensure level flight.

Step 6: Coilgun Research and General Information

Picture of Coilgun Research and General Information
Shoot cans, tins, or whatever your heart desires.(With the exception of others, unless they deserve it, not really). I am not responsible for you being stupid with this, If made right you could seriously injure or Kill someone with this.

Experiment with a different amount of capacitors to maximize the Muzzle Energy.

Equations:

-Potential Energy=(1/2)(capacitance in uF/1,000,000)(voltage in V)2
-Kinetic Energy= (1/2)(mass in g/1,000)(velocity in m/s)2

Equations for Capacitors in Parallel
-Capacitance(C) total=(C of 1st capacitor)+(C of 2nd Capacitor)+...
-Voltage(V)max= Lowest rated Voltage

Equations for Capacitors in Series
-1/(Capacitance(C) total)=1/(C of 1st capacitor)+1/(C of 2nd Capacitor)+...
-Voltage(V) max=(V of 1st capacitor)+(V of 2nd Capacitor)+...

-Power=(V)(I)

I-Current
V-Voltage
C-Capacitance

Disclaimer
I take no responsibility for your actions. If you shoot, shock, or otherwise injure yourself or others, Your
On Your Own.

Ideas, Comments, Questions? POST
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I have fawned a way to make the coil gun a automatic. I put a lm555 timer ,but you can use any of the 555 chips, to make it a automatic gun.

Xploder074 months ago
If you were to make a coil gun with just a single disposable camera circuit, you would just need to apply the power bank to where the battery would have gone, with a switch also on the positive wire, and apply your coil (with your lever switch on the positive wire) to the capacitor. (positive with positive, negative with negative) now if you used eight circuit boards,( keeping in mind on how I explained a single circuit board coil gun works) line them up in series, with each capacitor removed from them and put into a separate bank, the boards would all receive power evenly, which in turn, provide the power to the capacitors. My point is that nobody has to even follow this tutorial when they can simply do this, for one, you wouldn't have to destroy a perfectly good circuit board, and two, this way also allows you to use ANY KIND of circuit board as long as each one uses the same power source. Lastly, why would you want to waste so much money on building the guns body and/or case, when you can simply use the body of your choice water gun, nerf gun, etc. The inside of one is bound to have enough space to hold everything, and you can paint it the color of your choice when you finish putting it all together. That way it can save you the hastle on buying, finding, wasting much MORE money on the things to make one.

There's actually a very good reason you don't connect he boards and caps in series, that is because they wont balance correctly. Each cap has a different capacitance, it can be off by only a few microfarad or off by hundreds of microfarad, regardless, if you put them in series, the lowest value capacitor will stop charging first, and current will cease to flow through the loop at that point. (findamental property of a capacitor is that it stops allowing current to flow once it's charged) This is not a big problem if all your caps are almost identical, because you will get pretty close to the correct voltage on each capacitor. But if you're using cheapo disposable camera capacitors, then odds are your bank will stop charging long before every capacitor is fully charged. The solution is to use an active balancing solution, or a microcontroler, that systematically monitors the voltage of each cap and drains and charges them as needed to maintain balance. But that is an expensive and involved solution, the better method is to put them in parallel.
Further, you dont gain any power when putting them in series over parallel

3967 junits155 days ago

the soloution to this problem (caps in serial unbalanced) is to use the voltage divider principle. just put on each cap a low-tolerance reisistor in parallel. This will make sure that each capacitor will be charged. Please google the math for the right resistors.

Hitmanwilliam3 months ago

i am in a country that dont have exactly that cameras :P soo i cant easy make this and i need to know WICH coil-magnet wire i need can someone pls send a link to me? <3 thank you

Xploder074 months ago
i also wanna give thanks to instuctables user Plasmana. without his idea on his worlds smallest electronic shocker, i wouldnt have been able to use this idea for the coil gun charging circuit, and have been able to decifer rwilsford07's method.
Xploder074 months ago
for those of you who want to know EXACTLY on what connects to what using rwilsford07's technique, i drew up a diagram that'll make it much easier to understand. this way will also allow you to once again, use ANY curcuit board as long as it has all the correct componants shown in the diagram. the best thing about this diagram, if your a experienced solderer, you can desolder the components and solder them together OFF the curcuit board, which is best because it'll allow you to save A WHOLE LOT of space within your coil gun.
image.jpg
Xploder074 months ago
Why not just connect the circuit boards in series instead of in parallel, so each board can receive power evenly, and without having to cut out ANYTHING as well. You can make a simple cheap coil gun from a single camera circuit board without having to or cut anything.
Hitman3125 months ago

how to manualy connect a kodak ( disposeable camera ) transformer to wires to connect to the transformer and get high voltage?

I'm not sure for that application, but I made a taser like that.

Did u actually brand it with FESys

Hitman3125 months ago

does someone knows how to charge a capacitor?

Does this work?!?!?!

hrd26 months ago

how many batteries do i need?

sunwoongkim9 months ago
rwilsford07, may i ask your email?
Drake23121 year ago

hi uh what kind of capacitor did you use i' new to this so i'm not really sure, i know it isn't a super/ultra capacitor but if you could give me a link to a similar capacitor to the one used in this instructable that would be helpful thanks

I think I'll try this project this weekend.

qboid1 year ago
I have got myself two types of disposable cameras (FUJIFILM and Polaroid).
I can't tell where to cut the circuit board (and what the transformer looks like) so that the transformer comes out.
If It's not too much trouble could someone draw on the photos where I need to cut.
Thanks.
IMAG0041.jpgIMAG0042.jpg
qboid qboid1 year ago
The circuit board with the red LED. Do I need to cut it with the Transformer?
qboid1 year ago
When you say the capacitors should be rated 300VDC...
Do you mean each capacitor or all the capacitors in the bank must equal 300VDC to 900vdc?
Beachley qboid1 year ago
Each capacitor.
the design bears striking similarity to that of a high power emp device, will the gun emit an emp pulse when fired? http://www.wikihow.com/Build-an-EMP-Generator - (link to wikihow that shows how an emp device is created)
Brinith2 years ago
Where else can I get charger circuits from? A lot of the stores nearby me are not that generous.
nrickels92 years ago
I'm willing to bet you get better picture quality with one of those kodaks.
andyyudha2 years ago
Hey,I'm use circuit disposable fujifilm,how to make it into parallel ?
So I am looking at the semi automatic design, and I was wondering what exactly the injector solenoid did? Also if I used the "Boost Converter" that he also shows you how to build would you need the disposable cameras?
In reply to ishmal1103:
It's possible you've heated a transistor too much and it has burned out just replace every transistor but be quick and make sure it doesn't get too hot again or it will blow one of them out and then you will have to replace all of them again because you can't tell which one is the dead one (make sure when you get a new transistor its matches the one on the circuit board or it wont work e.g. the circuit board one might be negative positive negative (npn) so you will need to get a npn and not a positive negative positive (pnp) you can search up how to test between the two.
kacper001002 years ago
Hey, I recently managed to obtain a few pretty large capacitors (3x 3300uf 350v to be precise) and I was hoping to build one of these, I was just wondering if someone could recommend what size coil I should use and possibly the addition of more stages?
The theory behind coil guns is that they create a large magnetic field momentarily that accelerates your projectile, either through or away from the coil. The strength of the magnetic field is determined largely from two things, the amount of turns your coil has and the amount of power you push through it. You want the smallest wire gauge possible that doesn't liquify under the current you force through them in order to pack as many turns into your coil as you can in a given size.
The overall size of the coil is really up to you. You want the inner diameter to be slightly larger than your projectile. I wound mine around 1/2 pvc pipe and used that as a barrel. I hate supporting Radioshack, otherwise known as "The Man" when it comes to hobby electronics, but they usually sell magnet wire in the back that has a small enamel layer and is perfect for winding coils. Mine was roughly 2" long and only about 1/4" thick but worked great.

Those capacitors hold a lot of energy( E=1/2*Capacitance*Voltage^2 ) just over 600 Joules fully charged by my calculations. A simple design would be to just charge them up and discharge them all through your coil. In order to add more additions it gets more complicated with light triggers and high voltage transistors, but totally possible with something like an Arduino.
mbaker262 years ago
I am having some trouble im trying to do this with an electric weed eater any advice
Jagneeto2 years ago
Is the DC to DC HV Boost converter a substitute for the camera chargers in parallel? Sorry about the stupid question I just want to make sure.
coolkids2 years ago
do coilguns require high voltage or high current
Wow bro, you get everything i use from the same places. CVS 'cause i can ride my bike there, Harbor Freight 'cause they carry everything (including parring knives if i spelled that right and a sextant. and don't forget the machete and foot-long hunting knives!), and Radio Shack for the electrical components.
and just wondering, what would change if you hooked up a 2100v 1uf capacitor to the coil? wouldn't the performance turn out to be better? after all, it is a high voltage capacitor.
Not really if your charger charges at 300v and you have a 2100v cap at 1 uF then the cap will be charged to 300v 1uf you would see almost no change
Oh and the projectile would go much faster
You would need to up the voltage output of the charger bank and beef up all the wires. Maybe add some diodes to prevent blowing the chargers, and do some other things to make it work
Anyone have any ideas to replace the camera charging circuits with something more efficient?
Rebreg nms223 years ago
No unless you can make capacitors ( which I highly doubt) you can get them at Walgreens though.
mintybot Rebreg3 years ago
It sounds like he was talking about the actual circuit that charges the capacitor, not the capacitor itself. I've always wondered about doing this too.
fascinating, amazing how small you managed to make that SDPA-1 model. for simplicity of building would i be better trying to make a coil gun or rail gun? i have used that circuitry from disposable cameras to produce high voltage before but avoided the capacitors as they deliver terrible shocks if you go anywhere near their electrodes. i don't think i would try for making it automatic, that wasn't very clear how, but i might attempt to build one. great instructable.
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