Nail Katana




Introduction: Nail Katana

This instructable will show you how to make a fully functionnal miniature blade as well as a miniature scabbard - the former from an ordinary iron nail, and the latter from a strip aluminium can. Although not technically a true katana, I thought I'd use the name anyway.


Because I can now call it by its proper name.... a katanail, of course.

Let's get started!

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Tools, Materials & Prerequisites

At the very least, you need:

  • Nail, but not any type: must be ductile enough to be worked with hammer blows. I'm using mild steel.
  • Strip of aluminium can
  • Hammer
  • Anvil (or bench vice)
  • Metal file.. or dremel tool.
  • The usual consumables:
    - Tape, any kind will do
    - Sandpaper, several grits
    - Machine oil / WD40

That's really all you need to make a blade and its sheath, but if you want to go the extra mile (always a good idea),
make sure you have:

  • Paracord, gutted (or some other flat-ish fabric)
  • Sewing needle
  • Sewing thread, same colour as paracord
  • Tool for drilling small holes

Safety gear

  • Vital: Ear protection.
    Exposing your eardrums to the sound of pounding metal for an extended time, not a good idea at all.
  • Dust mask - The sanding process will generate some amount of metallic dust.
  • Face shield - In case your hammer blows somehow send projectiles flying off towards you
  • Work gloves - To handle the hot blade if using a dremel for polishing.


  • Noise: This project will generate a good deal of noise, so plan accordingly. Neighbours? Pets?
  • Time: It took me 2-3 hours total, spaced over a weekend. This includes:
    ~60 minutes of vigorous hammering,
    ~30 minutes of polishing/sharpening,
    ~30 minutes for the scabbard
    ~30 minutes of figuring out how to replicate the weaving pattern of katanas
    ~30 minutes of sewing the paracord together.
    I'm sure you could complete the whole project in a lot less time once you've got the details figured out.

Step 2: It's Hammer Time!

Now for the fun part.
Holding the nail head in one hand, place the nail tip over your anvil and hammer away.
Wearing a face shield is probably a good idea at this point. And ear protection.

Try to keep your blows centred on the nail. Hitting off centre will pinch the edge and produce irregular results.
Distribute your blows evenly along the length of the blade, but a little more towards the tip.
Choose one side as the edge, the opposite edge will be the blade spine.
Make the edge thinner than the spine. You will produce a curved edge by hitting more on the edge side. To reduce curvature, get more hits on the blade spine. Find the balance between your blows, the curvature and thickness.

You might notice the nail gradually curving upwards after a few dozen strikes. Just flip the nail over and continue.
To check if you've got a straight edge, look down the blade from one extremity.
The nail will increase in length as the blade gets flattened.

Bonus! Now is the perfect time to unleash any anger/frustration you may have experienced recently.

Step 3: Polishing, Sharpening

Use whatever means you fancy.

I used a round metal file to sharpen the edge, but not the whole length of it. Half the blade gets sharpened, the other half is the handle.

I used the file to smooth out the bumps on the spine, and also to shape the tip into a nice point.
Then some sandpaper and elbow grease to smooth the sides of the blade.
Final polishing with silicon carbide paper.
The final look of the blade will depend on how much effort you're willing to put in this step. Personally, I usually choose practical use over aesthetics. I don't mind leaving a few scratches on as long as it's usable.

Step 4: Scabbard / Sheath

Start by sanding the paint off the painted side of the aluminium sheet.
Trim down any rough edges.
Measure the width of your blade. In my case, the blade was as wide as a hacksaw blade.
Place hacksaw blade centred along the aluminium strip.

Fold top and bottom flaps towards centre. Important: The aluminium from beverage cans is very thin and will break along the folded crease if you put too much bending stress on the metal. Keep the folds round, avoid sharp bends

Tape the whole thing together.
Use pliers to open up the sides of the opening, this will make it easier to slide the blade in.

It doesn't look like much now, but we'll take care of looks in the next step.

(edit: corrected a few typos)

Step 5: Handle Wrapping

The katana-style handle wrap can be replicated easily enough.
Traditional katanas use leather strips, but I'll be using gutted paracord here.
Paracord consists of several (usually white) inner cores, surrounded by an outer sheath. By removing the cores, the paracord sheath can be flattened. Using this instead of normal paracord makes for a nicer finish imho.

You need to know how much paracord to use. In my case, 120cm of paracord was just enough for an 11cm scabbard.

Then you need to know whether to start wrapping from the midpoint of your cord or not.
If you start from the middle, you'll end up with equal lengths once you're done wrapping.
If not, you'll have a long end and a short one. This is good if you're making a clean (knot free) shoulder strap, like I did here.

I did not take any pictures of the paracord wrapping process, so I demonstrate with some rope and a hacksaw blade. Basically, you want the riding turn to be in the same direction for each cross. Full wrapping instructions are in the picture annotations.

Once you're done wrapping, tie off an overhand knot. To keep the wrapping tight and secure, we'll use some sewing thread next.

Step 6: Sewing

If you've never done any sewing before, and/or if you believe sewing is only for the ladies, think again.
Sewing is an exceedingly useful skill - in everyday life, in emergencies, in survival situations... It is fairly quick to acquire and costs practically nothing (except your time, perhaps). I think it should be in every self-sufficient person's skill repertoire.

Sewing instructions in the picture annotations.

Step 7: Done!

There you have it, the Katanail. They make fantastic homemade gifts!

Something to keep in mind:
If you're using an iron nail (or anything that's going to rust) you can slow down the rust with a light coating of machine oil or WD40, although there exists some debate as to which one is better, you'll have to try for yourself.
As with most tools, the best way to keep it in good shape... is to use it.

Step 8: Extra Resources

Fantastic tutorial on katana handle wrapping, very well documented:

Work hardening - effect of the hammering process on metal hardness and ductility:


Another nail knife instructable, Stunning workmanship

Tools Contest

Participated in the
Tools Contest

1 Person Made This Project!


  • Sculpting Challenge

    Sculpting Challenge
  • 3D Printed Contest

    3D Printed Contest
  • Motor Vehicle Contest

    Motor Vehicle Contest

14 Discussions


5 years ago

That's really cool, do you think a shoelace would work instead of gutted paracord?


Reply 5 years ago on Introduction

Hmm, I see no reason why it wouldn't work. As long as you're happy with how it looks, and as long as it's secured properly, you should be fine.

Now that I think about it, my shoelaces are flat!


5 years ago

Nice! Phoenix beer :)


5 years ago on Introduction

Good Job. It looks like a fun project.

The nail you couldn't put a dent in is a concrete nail. They come hardened and are plenty tough. If you wanted to make something out of it heat it red hot and let it cool slowly to anneal it. It will probably still be tough to work with but at least possible. You could even re-harden it when you were done.


Reply 5 years ago on Introduction

Thanks! Lots of fun, very true. After hammering for a while, I get into this really calm, almost meditative state, very focused on the task at hand, and everything else ceases to exist for a while.. I love it.

Ah! A concrete nail, so it seems!
Not sure if it's galvanized though. If that were the case, I would have to be extra careful with the fumes, right?
Also, concerning re-hardening: do you mean quenching?


5 years ago

Nice instructable! Very well documented! Keep it up!


5 years ago on Introduction

That would make a pretty neat letter opener.

Great first time instructable, the comprehensive photos left no stone unturned. :)


Reply 5 years ago on Introduction

Thanks! I've been an instructables member for long enough - it's high time I contributed something to the community. I'm glad I did. :)


5 years ago

Fun project. My son would love it.