Introduction: DA-OTF Hidden Blade: Functional and 3D-Printable Hidden Blade Prop

Picture of DA-OTF Hidden Blade: Functional and 3D-Printable Hidden Blade Prop

Have you ever wanted your own Assassin's Creed style hidden blade? Well here it is!

This hidden blade is based off of Ammnra's blade and features the DA-OTF(Double Action- Out The Front) Mechanism to propel the blade inward and outward with the flick of your wrist. I tweaked the hidden blade to make it operate smoother and fit more comfortably on your forearm. I have high hopes of eventually selling these bad boys to fellow cosplayers and Assassin's Creed fans.

The Mechanism: go here for an OTF Knife explanation. I recreated this mechanism by basing it off of someone called Amnnra. He does not sell his creation and I want the public to be able to have it. Anyway, if you want to see this in action check out one of his videos here.
His functions almost the exact same to this one except this one has gotten the kinks worked out and has a two tier extension, which allows for a longer more realistic blade.
This is basically what happens inside the blade casing: A piece of string is attached to a ring on one side and a rubber band on the other. The rubber band and string rap around a wheel and turn it when the ring (attached to finger) is pulled. When the wheel turns it activates the OTF mechanism which propels the blade forward. There is a special piece that locks the tiers so they dont retract unwantedly. To retract it you simply pull the string again and the OTF mechanism will retract it. If this made no sense to you, click the links of the words above. they will direct you to videos that will help you understand. :)


042lej (author)2017-10-05

Mechanism does not work.

gowen1291 (author)2015-04-23

I would like to purchase your designs in order to build your hidden blade. Please email me at I have access to a 3D printer and could even build you one if you'd like :D

HadiR6 (author)gowen12912017-08-09

i can sell you one?

RyanM108 (author)2017-06-20

No files?

RyanM108 (author)2016-03-15

He actually does sell these:

This is my version of the hidden blade

you should check it out! Very nice looking blade here sir!

PizzaPlanet (author)2015-06-04

here you guys go

GeekS (author)PizzaPlanet2015-11-18

is the scale in cm or inches? I know basically nothing about 3d printing, and dont know which one it is.

PizzaPlanet (author)PizzaPlanet2015-06-04

follow the youtube link and download google sketchup.

m8ayrbKs (author)2015-10-29

i would like to get a set of the printable designs without having to pay to go pro please, if you wouldnt mind, that would be a great help!

TheonlyrealWaldo (author)2015-03-30

I'd like to purchase one

kampy00 (author)2015-02-01

Robboy700 (author)2014-11-02

was wondering. would it be possible to make a version without the ring and string mechanism? say like the ac4 blades but instead of just being activated by a flick of the wrist and tensing of a forearm muscle you use a certain finger formation AND a flick of a wrist and the tensing of a forearm muscle. the blade would lock and in order to make it retract you do the same thing except with a different finger formation

Gh05tWh0W4lk5 (author)Robboy7002015-01-01

I'm sure it is possible but there would be a very very complex design. If the problem with the string and ring is the annoying feeling you can make the string longer and thread it through a thumb ring and then connect the end to a third finger so then it can only be opened and closed if the thumb has been completely extended as well as the third finger and the flexing of the wrist. Hope this helped.

nsaul (author)2014-11-18

I think I speak for all of us when I say I would love an stl/cad file for this

jlsajfj (author)2014-11-10


LarryM1 (author)2014-10-15

If I may, I would like to see the PDF files for this instructable as I would not like to pay to be able to see them. I am in the progress in making a AC4 cosplay costume, and all I need now is the hidden blades. I do not want to waste my money on a toy object that could break in less then a few uses; I would like to make something durable that is worth my money to be spent. Thank you for reading this, just send the files if able to me. Again, Thank you.

starlots (author)2014-05-11

Can we please get the files for this? Looks really cool!

lolzder (author)2014-05-03

Were can i download the 3d print files?

Jo-dan (author)2013-10-22

how does the 2nd tier lock/release? its the only part of ammnra's design i dont understand

maysen22 (author)Jo-dan2014-03-03

It is activated by a little wedge that is controlled by a slider. So when the blade goes out the wedge goes behind it and locks both tiers. Hard to explain but hope that makes sense.

pyrodaclown (author)2014-03-03

Where can we get the file for this? or where can we buy one if you do plan on selling them?

fjohnson8 (author)2014-01-07

where can i download the plans for this

p8ntballsniper87 (author)2013-09-12

So... what's it take to get the blueprints for that bad boy?

rooseveltjusto (author)2013-08-18

You want us to vote, but we can't see the project to evaluate along with the other contestants? Fail, my friend...

Gh05tWh0W4lk5 (author)2013-07-31

how do you vote?

damien-issa (author)2013-07-29

I would like to retrieve the plan your project.
How to do this?

DukeRDF (author)2013-06-29

it would be awesome too if u post some link to download the blueprints of 3D pls!! *-*

AF-Geek (author)2013-06-13

Interesting, but not really an Instructable without an 'instruction' on how to do it. Upload STL file(s), and explain the construction a bit better, and you'll have my vote.

rug (author)2013-06-11

please upload the file for this :) i cant wait to print it

umerji1000 (author)2013-06-09

yeh i would like the file too, i have already voted for you :)

mbroadwater (author)2013-06-03

Is the file available somewhere? I'd definitely vote for this project if it was.

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