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A while back I found instructions for a clever office supply bow and arrow and was inspired. I decided to step things up a notch. In the end I had a nifty little "crossbow" that straps to the inner arm, perfectly concealed by a loose sleeve. With just a flick of the wrist, your classmates won't know what hit them!

This is the second incarnation of the design. The first was held together entirely with gorilla tape and I only had enough pictures for a slide show.

**Careful!**
Though not as powerful as other designs, this thing can still do some damage. Do not point it toward the face, it could easily take out an eye. Do not aim anywhere that can potentially damage something, it's awkward aiming with the forearm, so its accuracy can be hit or miss (pun intended).

Step 1: You Will Need...

Materials:

At least three Bic ballpoint pens
A thin rubber band*
A clothespin*
Several craft (Popsicle) sticks
A length of strong thread*
Duct tape (No project is complete without it!)
A ring (optional)

*take care selecting these items. Too strong a rubber band can't be held back by the clothespin. Too strong a clothespin will break your thread. If everything is too strong you risk yanking the whole thing off your arm when you go to fire.


Tools:
I was able to rig one of these with mostly scissors and a roll of gorilla tape in the back of class, so don't sweat the details. However, I have found these to work quite well:

Scissors
A hot glue gun
A small-bit drill
A fine-tooth saw
Duct Tape (So important it deserves to be named twice.)

Step 2: All Your Base...

The base of this rig is made out of craft sticks. I used seven, but the exact number can vary if you wish. I suggest keeping it about the width of the wrist to prevent it from shifting around.

What is important is that you make sure you use an odd number of craft sticks.  While most of the sticks are flush, the middle one is pulled back about 1 1/8 inches. (all my measurements are arbitrary and based on how things fit together. Your measurements may vary.) This is where you will attach your clothespin.

Bind the sticks together tightly with tape. You may want to push it down onto your arm afterward to get it to contour to your wrist.

Step 3: The Pen Is Mightier...

Now it's time to take apart those pens. They should come apart easily with a little effort. Apart form the cap, these pens are made with four parts with names I am about to make up: The nose piece, the ink cartridge, the shaft and the end-cap.

Take one of the shafts and shave it down to a length that will fit sideways in your sleeve without making a noticeable bulge in the fabric. Mine came out to a little less than four inches.

Find the middle of your shortened shaft and make a hole all the way through. I was able to do this with an x-acto knife and screwdriver. If you have the tools, I'd expect a heated piece of metal to work pretty well. Make the hole wide enough for the nose piece to fit snugly inside.

Cut some notches in the ends of the shaft to hold your rubber band. Now attach the entire thing to the body of the crossbow with tape and/or any other fasteners/adhesives you are using, with the nose piece centered over the gap left from the uneven middle craft stick. Make sure the tapered end of the nose piece points outward.

Step 4: The Guide Rail

Take the second pen shaft and split it lengthwise in two. Try to shave down the edges until they are as straight and smooth as possible. The rubber band will be flying through here and you don't want it to snag.

Take your clothespin and drill a hole through the two ends you pinch together. Position the clothespin on the body of the rig, over the craft stick that sticks out on the back end. Make sure the hole in the clothespin is far enough back so as not to be covered by the craft stick, and secure it down.

Take one half of the split shaft and shorten it to fit between the closed end of the clothespin and the nose piece centered between the crossbow arms. Glue it down.

Step 5: "Twang!"

Now comes the tricky part. Here is where you construct a special fitting for your rubber band that fits into the catch (the clothespin)

1. Take a thin strip of duct tape and roll it up part way. Roll with the sticky side in.
2. Place one of your end caps on the edge of the unrolled end, on the sticky side. This part will hold the bolt (Ink cartridge) and keep it from falling off the rubber band. Place the rubber band just behind the end cap.
3. Cut partway in on the strip of tape on each side, behind the rubber band and before the roll. Fold these new tabs into the sticky area between them. Press what's left up the sides of the end cap. To be safe, you will want to secure the other side of the end cap with a shorter piece of tape with similar tabs cut into it. Do not make another roll with the second piece. This tape creation has to bear the tension of the rubber band, so try to make it as secure as possible.

Now time to "string your bow." The rubber band stretches around the arms, fitting into the notches you cut into the ends. The tape assembly should sit in the guide groove made from the half pen shaft. The rolled end should fit in the clothespin when pulled back.

If everything is in order, go ahead and tape on the other half of that pen shaft over it. Make sure to only use tape here as it attaches to moving parts and must flex accordingly. Anchor one end of the shaft to the top of the clothespin, and the other to the crossbow arms. You may have to glue in something to raise the top half of the groove up high enough that it doesn't slow down firing.

By now it's suitable as an office crossbow. Now on to the part that makes it unique...

Step 6: Finishing Up

Take your remaining pen shaft and split it in two lengthwise, like the last one. Glue it to the underside of the base along the middle, right under the hole in the clothespin.

Tie your thread to the outside arm of the clothespin before stringing it through the hole on the bottom side leading to the half shaft you just glued in. If your thread isn't strong enough to pull the two ends together you may want to double it up. After the clothespin, string the thread through the half shaft on the underside of the rig. An easy way of doing this is threading a sewing needle and dropping it through. Tie the open end to a ring, or into a loop.

Now it's time to add the straps. I made mine out of strips of tape, layered sticky-side in, fastened around my arm with more strips of tape. I made them kind of hastily to illustrate. If you have a good method to fasten the straps I would enjoy some feedback.

For ammunition, take the ink cartridges and cut them down to size. You want the back end to sit in the cup of the tape assembly when pulled back, and the point to fit closely to the nose piece without going in.

Step 7: Annoy the Heck Out of Your Friends and Coworkers

Now time to strap the whole thing to your arm and try it out. Keep the ring-on-a-string on a short enough leash that it pulls open the clothespin when you bend your wrist back. Put it on your finger. Pull the tape assembly back into the catch (clothespin) and load in one of your bolts (shortened ink cartridge). Now you're ready to put tiny dimples in something!

Make sure it is strapped to your inner arm if you want to hide it in your sleeve, that way gravity will pull it open allowing the your shot clearance. I would post pictures of it in my sleeve, but it hides so well it would just be a picture of my sleeve. What this contraption lacks in strength it makes up with in the whole "What the #&@% was that!?" factor.

Bonus features:

For added strength, you can wind the free end of the rubber band around the nose piece.

Should the string break, you have a fail-safe. Push in the back of the clothespin with your free hand (You'll want to know where that is anyway, it's easy to bump it on something and shoot yourself in the hand).

Push the ink cartridge slightly into the nose piece (that's where it was made to fit). Now it won't fall out when you point your arm down. Make sure not to press it in too far, or when you go to shoot, it won't budge.

Add a safety by lengthening the string so it will only fire when the ring is on the second knuckle of your finger. Now when the ring is all the way down on your finger, you don't have to worry about accidentally shooting yourself in the chin when you try to pick your nose. When you want to get ready to fire just discreetly push the ring up to the middle of your finger.


Now just get creative! Add a place to hold extra bolts. Find a way to improve it (shouldn't be too hard).  Personally, I've always wanted to see one of these rigged as a trap inside someone's desk drawer.

<p>just finished making it, works great for pranking and messing around with friends. Keep doin what your doin man!</p>
<p>That looks AWESOME!!!!! can't wait to make it.</p>
<p>cool</p>
works awesome
<p>nice</p>
<p>nice</p>
<p>Sweet!</p>
<p>BEST.WEAPON.EVER.</p>
I've attempted to build this while removing the string, because pressing the clip feels satisfying. It still works! Still can't find a clip, but replacing the popsicle sticks with two pieces of cardboard (with the lines of both pieces intersecting) makes it fairly sturdy! All in all, this is a great project (for all ages) that has room for customization.
<p>If you don't want it to fall when your hand is down you should have the clip hold the arrow. Why not?</p>
<p>I'm want to try to modify the materials to shoot across the room. The jerk who throws crap at people won't know what hit him. XD Thanks</p>
<p>I want to say one word.</p><p>AWESOME</p>
It is awsome
Amazing just amazing totally going to make
is there any other substitute for the pens?
Dude. That is so awesome I'm gunna DIE! I will totally make this!
How far does it shoot
BTW, i have possible ideas for one that fires multiple instead of just one.
Thanks man! i have been looking throughout this whole site and yous is by FAR... THE BEST ONE! And it works good. When i brought it to class some kid tried to copy it, but he somehow shot himself in the face! (so i shot him afterwards)
I found that a scew driver and a drill work best instead of an exacto knife. (More kid friendly) ;D
Is their any other device I could substitute the clothespin with
Something I'm looking forward to getting sent to the principal's office for c;
I realised why it needs sturdy string,i keep flicking my wrist hardly and the string just breaks
I want to find an Instructable that is a K'nex version of this crossbow.
I don't understand how to tie the string to the clothespin and connect it to the ring...
Drill a hole through both both tabs on the end you pinch together. Tie the string through the hole on the outside tab, then run the loose end through the hole in the inside tab and underneath the whole crossbow.
HAHAHAHAHAHA!!!
thanks!!! it works perfectly its very comfortable! and at the first shot i accidently&nbsp; shot my finger and it hurt alot but evrybody was afraid of me with that thing :D<br /> <br />
It's the same for me with a blowgun I made.
Outstanding! Spread the fear! &gt;:D<br /> And hey, now you know it works really well.<br />
fake hand
Well, of course it's fake, lol. You try taking a picture of your own hand while holding your arm flat down on the table xDDD
With a crossbow strapped to it lol
Actually that's my hand. It's directly under the light which is flattening out the features or something. Though it was a little tricky getting this shot.
i just got finished making something similar to this. it's like one of those spring loaded spears, but it is a down sized version that you hold exactly like this. it only took 3 k'nex, a rubber band, and some gorilla tape. I'm actually surprised at how well it works when i use it right. i do plan on making the crossbow shown as well too.
i took the seemingly obsolete remainder of the pen from step 3 and put it in the roll.
Ooohh... that was smart.
as i said before, i didnt cut another pen; i used previously cut ones.
Err... I made mine and it shot the ink cartridge a foot or less, and it just dove down... Any solutions to make it shoot further and stronger?
I'd just tighten the rubber band. I usually loop mine around the nose piece.
can you use cardboard?
Yes, I think, but this wouldn't be so resistent
nice work, looks sweet. for the 3.0 version, u should make it so u cant see the crossbow at all<br /> <br />
How do you mean? It's already pretty much completely concealable under a long sleeve. I'm always up for refining the design, but I'm not sure how to get it any less visible unless I used 'The One Ring' for the trigger.<br />
I'll use a ring-ized paper clip
i really dont think it could be anymore descreit
Can you use also skewers for ammos?
If it fits I don't see why not. I wouldn't point that at anybody, though.
Thanks! Anyways, I think I would tape the end. <br>We love duct tape! <br>We love this proyect!
hey ducttapeninja could u make a hidden blade like this instructable

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Bio: I just like to make things. I dabble in a lot of mediums and usually don't like to spend money on parts, so most ... More »
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