Introduction: Hidden Blade

Picture of Hidden Blade

Almost Ezio-quality hidden blade :)

Full costume or 2010 Halloween can be found at the link below:

Step 1: Ingredients

Picture of Ingredients
This whole blade was pretty cheap. Price breakdown:
  • Drawer sliders (2) @ $3 for 2 sets (Axmans surplus store!)
  • Ring @ $1.50 each (Target clearance shelf)
  • Rubber bands @ practically free...
  • Letter opener (AKA blade) @ $1 each (Office Depot)
  • Cotter pins (2) @ ~$0.20 each (Hardware store)
  • Nuts-size 6
    • brass ones (11) @ $0.09 each (Hardware store)
    • steel ones (~12) as filling on long bolt @ $0.08 each (Hardware store)
    • size 10 brass @ $0.25 each (Hardware store)
  • Washer
    • size 6 (8 of them) @ $0.08 each (Hardware store)
    • size 10 (8 of them) @ $0.08 each (Hardware store)
  • Bolt
    • tiny size 6 (8 of them) @ $0.08 each (Hardware store)
    • 2" long size 6 @ $0.08 each (Hardware store)
  • L-brackets (8 of them) @ special discount, I got 100 for 35 cents :)

That adds up to about $10.50
Not bad!!!

Step 2: Assembly Step 1

Picture of Assembly Step 1

Grab one of the drawer sliders and slide it as far apart as it will go. Measure on your arm about how long you want the casing of the hidden blade to be. (mine is about 7~9 inches, i forget exactly how long).

Grip the slider firmly and saw off the extra slider (the wider part)

You should be able to slide the thinner slider part out of the wider one. Do so. We are going to throw away the thinner part, but first we need to get the other smaller piece attached to it.

Bend down the piece shown in the 3rd picture with a pliers. Carefully (and close to the ground) slide off the piece with the ball bearings. Keep this piece along with the ball bearings.

Refer to picture 5 to see what we are keeping.

Go to next step.

Step 3: Assembly Step 2

Picture of Assembly Step 2

Pick up that smaller piece that used to have the ball bearings on it.

Cut it so that it is only six holes long (as in picture).

Estimate where you will want the blade to be fastened. 

Drill holes through blade and slidy thingy so that you can put bolts through them both along with nuts to tighten them.

Tighten the nuts and bolts securely (as tight as they go!).

Then, put 8 of the ball bearings back on, on the back / bottom 4 holes on each side (see picture 6). Slide the whole thing back into the large slider (picture 7).

Examine its beauty and try it out :) just don't lose the ball bearings!!!
Next step!

Step 4: Assembly Step 3

Picture of Assembly Step 3

Alright, this is a short step.

We are working on the side of the blade casing with the butt of the blade. This is to keep the blade from sliding into your elbow / arm / face / whatever. It is the back of the casing. NOT THE POINTY END!!!

Drill a small hole (just wide enough for your size 6 bolt) through the L-bracket just above one of the other holes already in it, and near the bend. (picture 1)

Drill another hole to match this one on the casing (not the blade or the slidy thingy we attached it to), the wide casing.

Attach as shown in pictures 2 and 3.

Tighten a bolt / nut. (tight!)

Easy! Next step!

Step 5: Assembly Step 4

Picture of Assembly Step 4

Make another one of those L-brackets have an extra hole in it. Attach it onto the other L-bracket as shown in pictures 2 and 3.

Since this step is so short, I will add another part to this step... (also, I forgot to document it with pictures, kinda, but its easy anyways!)

Remember that wider slider thing from the first assembly step? get another one of those, exactly the same length, through whatever means necessary!

Thats all. Its shown in picture 4 also as the wide slider below the one we just made. We will also be using it in the next step!

Step 6: Assembly Step 5

Picture of Assembly Step 5

Another easy step. Drill a hole in the other wide slider to attach to the last L-bracket attached. Pretty easy to see in the pictures.

Step 7: Assembly Step 6

Picture of Assembly Step 6

The key. This is what allows you to open and close the blade.

This step uses the 2" long size 6 bolt with a whole jumble of nuts and washers on it to hold everything in place. You will also need the longer of the two cotter pins that you have. Along with 2 more L-brackets.

Add a size 10 nut to the cotter pins before bending them so that they will remain together while the blade is in use.

Bend the cotter pin to have one end be the pin that sticks into the casing and the other end form a loop to tie a string to. (do this part at the very end of the whole assembly)

Have the L-brackets facing each other.
Have the cotter pin in the middle.
Maybe have  larger washers around the cotter pin (?).

Just follow the pictures, easier than words!

Step 8: Assembly Step 7

Picture of Assembly Step 7

In this step we will attach the "key" from the last step and mount it onto our casing. It will go on the back of the second wide slider that we cut.

Drill two holes appropriately spaced to fit the "key" into the wide slider.

Hold it on and judge about where the pin will need to go through the casing. Drill a long and wide gouge into the casing there. (Picture 3)

To place it in the right spot, you must have the key already bent how you want it. The tip of the key's cotter pin must fall onto the first wide slider when the blade is all the way out. The key's cotter pin tip should be designed to catch the blade when it hits something and tries to go back. This is what locks the blade!

Continue to the next step once you are satisfied with this.

Step 9: Assembly Step 8

Picture of Assembly Step 8

Almost there! 
Grab 2 more of those L-brackets. And a pliers...

Bend the L-brackets flat to start. Then bend them as shown in picture 1 on the right. Bend both sides to look like this.

After looking at the next step you might have a better idea of how to do this...

Step 10: Assembly Step 9

Picture of Assembly Step 9

Last step!!! Woot! (I never thought I would ever type that)
Even better, half this step is optional!!!

They don't do anything, but if you want to know how I made mine exactly, then read... I'll tell you when to listen again for real.

Grab two more L-brackets and fold them over themselves.

Hold the "key" in place and hold the previous step along with this step in place too while you carefully push a small bolt through the holes (all the way through the key's L-bracket  holes) and attach a nut from the key's side. Tighten as tight as it can go. Then fold and crimp the L-bracket on the bottom over the bolt head. (Picture 4)

Alright, Listen again. You DO have to follow these instructions...

Fit the two wide sliders together as shown in picture 5.

...I must admit, I forgot one picture... You should have one cotter pin left over, right?
Well, it simply goes right through those holes of the L-bracket. (Picture 6). Then bend the ends of the cotter pin so it can NEVER get out   :)

Ok, I also lied, there is one small step left.
Attach rubber band over the cotter pin (look at finished pictures) of the key.

Also, tie a string (I used kevlar thread, use whatever you want) to that loop on the key's cotter pin. Have the string attach onto a ring that goes on one of your fingers (tie it to the ring). Tune the length of the string so that the hidden blade operates as you like!

To open or close blade, pull on string and hold the blade either up or down, or fling it open / shut. Release tension in string to lock it into whatever mode it is in! The key catches underneath to keep it open, and pushes against the blade to keep it firmly still when closed.

Step 11: Finished

Picture of Finished
Enjoy your hidden blade! I found that mine can stab through everything I've tried so far!
CAUTION: Do not stab people, etc...

I made two of these exact blades for a halloween costume (each for a different person). And one other for my younger brother of a different (worse) design :) There are some fun videos we made with it though, it does work, just not as pretty!
I have not finished the vampbrace completely that will hold these, but I do have designs and the materials :) The rest of the costume is on the way, not showable yet though!

Step 12: Strap-on :)

Picture of Strap-on :)

Here are just a few pictures of the blade with the straps and glove attached. More pictures can be seen at the link at the top of the page!


deadpool33458 (author)2017-11-17

When u close your hand does it automatically go back in

OjasJ1 (author)2016-08-21

Sapphire88 (author)2015-09-30

What do u recommed using to have it attached to my forearm? Rubber bands? Velcro strap?

Onyx Ibex (author)Sapphire882015-09-30

I recommend elastic bands. I used elastic bands sewed to a glove in the front and a simple elastic strap in the back (lower forearm). Velcro would also work really well

Sapphire88 (author)2015-09-29

With 1 drawer slider, can i make 2 blades?
If not i havent bought the materials yet so just wondering

Onyx Ibex (author)Sapphire882015-09-30

Actually, I used 2 small length drawer sliders to make 1 hidden blade. It depends on how long you want the sliding distance inside the blade and on what length draw sliders you start with. I got my drawer sliders dirt cheap so I had no qualms using 2 to make 1.

Sapphire88 (author)Onyx Ibex2015-09-30

For 1, what size do u recommend?

Onyx Ibex (author)Sapphire882015-09-30

8" is a rough estimate of the length of each half of the hidden blade. So you need two 8" sections.

Sapphire88 (author)Sapphire882015-09-30

Sorry, ment to say 2

Sapphire88 (author)Sapphire882015-09-30


Sapphire88 (author)2015-09-29

Can it be retracted when the string is pulled again?

Onyx Ibex (author)Sapphire882015-09-29

When the string is pulled again, the lock disengages and the blade can slide back down (not spring forced down though)

Sapphire88 (author)2015-09-29

Can it lock in place?

Onyx Ibex (author)Sapphire882015-09-29

yes but not for a ton of force

Sapphire88 (author)Onyx Ibex2015-09-29

Ok good to know!

RedneckAssassin (author)2015-04-11

OK, In the drawer sliders, Do I saw off the drawer that the blade goes into?


I think I understand the question which tier do you cut

I'm not quite sure I understand your question but I think the answer is yes. You want to cut the drawer slider to the right length. You are only cutting one end of the drawer slider though. Is that what you are asking?

can u sell me two of these i honestly will send you mony please respon

Green X (author)2014-05-13

nice I could use this

ThePokefan101 (author)2012-12-04

Hi there,
I was just wondering what kind of drawer slides you used, and whether you have any links to websites where I could buy them.

Onyx Ibex (author)ThePokefan1012012-12-04

I would try looking locally as it will probably be cheaper than online (shipping). You are looking for something like this (amazon). The other reason I would recommend shopping locally is that you get to actually see what you are buying. It can be hard to tell online what you are buying a lot of times. Although I'm sure you know all of this already. No promises that that is the right drawer slider, but it looks right to me in the picture and is the right length. Good luck!

i would really like to make that but i cant because im in greece.if i could i would buy 2 of those for the double price

regby (author)2013-01-11

How does it retract????

pokemech (author)regby2013-12-12

I believe it's just gravity, the lock connected to his finger opens and he holds his arm down to extend it, then he loosens his hand to close the lock. To retract it, he holds his arm up and releases the lock, then locks it again once it's in.

jamez1998 (author)2013-08-12

thanks, still working on it, i'll finish eventually

ChoiBoy0527 (author)2013-07-30

You can also make the 'key' sideways to get a slimmer design

rejectameric (author)2013-06-08

Thanks! Having a hard time, but I'll get it eventually!

didibemi (author)2013-04-10

VERY NICE. I just loved your instructable and I'll be doing it this month. Perfect, for real!

Slrman (author)2013-03-30

Ideal for a terrorist neophyte. As usual, the TSA would be helpless against this. But they are mostly useless anyway.

kramerllama (author)2013-01-14

I feel like you could use a smaller U bracket and smaller bolt for this step, and would reduce much of that clutter from the nuts.

tetrahydrawho (author)2012-12-30

I think im gonna try a double spring action so its auto in/out...ill let everyone know how it goes

amcmorris1 (author)2012-12-14

I've been trying to make a hookblade (without the blade) for ages, I would use it as a climbing hook for Parkour.. can someone give me some help?

Onyx Ibex (author)amcmorris12012-12-15

you mean basically a crowbar shape? but lighter I assume. Were you thinking retractable? if you let me know a few more details such as the length desired I could draw and send some designs to you if i think of anything. As a separate suggestion, I have had some success in pursuits by using poles with a hook at the end (8 foot long poles) and grips twisted into the pipe. The pole allows you to vault, swing and hook assuming you can climb a thin pole and know how to vault. It comes in quite handy and allows you to reach many inaccessible places. The downside being that it isn't concealed easily...

Dr.Ike (author)2012-12-13

You could probably use a pen tube instead of all the nuts.

Onyx Ibex (author)Dr.Ike2012-12-14

ideas like that are why I love ibles

ezra0128 (author)2012-11-02

is it retractable

Onyx Ibex (author)ezra01282012-12-04


Naitsirhc (author)2010-12-11

Is it wise to be instructing people on how to build concealed weapons? What happens when this technology makes its way into our schools? Seriously. Many schools already have security and metal detectors. One kid gets stabbed by a weapon like this and instead of starting the day with the Pledge of Allegiance or kids are going to be starting the day with a morning TSA Style Pat Down.

Under_miner (author)Naitsirhc2010-12-20

dude, I think that any kid even if they are stupid wouldn't be that stupid.

Naitsirhc (author)Under_miner2010-12-20

you are underestimating just how stupid, stupid kids can be.

theubster (author)Naitsirhc2011-01-05

yeah, but you are assuming that most kids will take the opportunity to stab their enemies in a school. Not the case. If a kid is going to be stupid or try and stab someone, not knowing how to make and assassins creed style blade will not stop them. A regular old pocket knife will do. Or a chair. Or a pencil. Or a gun. We are surrounded by weapons, some more potent than others, and we have to trust one another enough to assume we won't be stabbed at any given moment....

Naitsirhc (author)theubster2011-01-06

Yeah its true if a kid is pushed to the edge and they snap they might try to get that kid with anything they have at there disposal, but many kids will bide there time, take time to make a hit list and that kind of stupid thing. Kids can have a flair for the dramatic. You can't tell me that the Columbine kid wasn't thinking about "The Matrix." when he shot up his school.

Ringley (author)Naitsirhc2011-01-08

It doesn't matter if a kid is going to take their time or not... There are many more instructions for making weapons all over the internet. Complaining about this one specifically isn't going to do anything to hinder the hundreds, even thousands of others that are posted all over the web.

If a kid is stupid enough, and angry enough, to want to kill others, you can't blame the people who are teaching others to make weapons. Knives, guns, and any other kind of weapon DON'T kill people. People kill people. Someone with the intent to kill others is going to find whatever way to do so that they can, with or without the internet's help.

As far as your comment about The Matrix goes, maybe he was, and maybe he wasn't. The point is that it isn't the media that is killing people. Games like Grand Theft Auto or Saints Row aren't telling people that it is okay to kill others. The only kids that will be "stupid" enough to start having thoughts like that are kids who have some kind of mental instability. There are far more normal, non-violent children than psychopathic potential murderers in this world.

mountainman123 (author)Ringley2012-10-28

I think you're over estimating our stupidity.

lunius (author)Ringley2011-01-22

Exactly. Many people who view this may be like me, wishing to make a prop version for recreational use. My Parkour group is beginning to lean towards an Assassin's theme, and making a paper or cardboard blade like this would do wonders for our demo videos.

I have seen much worse stuff than this on the internet.. I can tell you how to make napalm at home for roughly $5 per gallon, I can show you how to make an RGD-5 Hand Grenade, how to dig and cover a pungee pit to match the location. I can tell you how to make a throwing knife out of a blank CD, and a caltrop out of needles. I can build a small forge and forge knives with old soda cans. I learned all this from the internet, and have not ONCE seen ANY of these employed in a school. At my high school, there have been bomb threats and gun threats, and many kids carry knives for their own protection, but not one of them would bother attacking someone in a place with cameras and police officers.

Even mentally unstable people have a basic grasp of common sense.

pipsqueakboy (author)Naitsirhc2012-10-22

Its not like he's teaching them how to make a shank. Hes not teaching them how to make a weapon specifically to shank someone. Besides, If a kid tried to shank someone at school. why make this. They would use a pencil instead anyway.

mrmerino (author)Naitsirhc2012-09-27

Start the day with the Pledge? I start third hour with the Pledge.

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