Some other models in Naruto Collection:
Flying Raijin Kunai 
Shuriken

Kunai

Dimensions (total):

Length : 30.00 cm
Width : 6.00 cm
Height : 2.60 cm

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Blade

Length (Total) : 19 cm
Width : 6.00 cm
Height : 1.40 cm
Length (Without Connector) : 16.00 cm

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Handle :

Length (Total) : 14.00 cm
Diameter (Grip): 2.60 cm 
Length (Grip) : 9.80 cm
Ring Size : 4 cm

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1.0 Kunai (One Part)

If you want to print whole kunai from one model this is what you need

1.1 Kunai.3mf

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2.0 Two Part Models

2.1 Top & Bottom Parts

If you want support-less printing you can use two files below

Gluing them after printing
Those two are quite big models with 100% size they might not fit on some printers with smaller build surface

2.1 Kunai Half.3mf

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3.0 Blade & Handle

This version has a seamless joint with a tolerance of 0.1mm
You can download Blade 0.05mm.3mf if you prefer 0.05mm tolerance same for 0.15mm and 0.2mm

The blade is inserted into the handle
3.1 Blade.3mf

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Handle is optimized to be printed vertically ( ring part at the top )

3.2 Handle.3mf

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In summary 

You can print the whole kunai by printing:

With Seal Version

1.1 Kunai.3mf
OR
2.1 Kunai Half.3mf + 2.1 Kunai Half.3mf (Same Model Twice)
OR
3.1 Blade.3mf + 3.2 Handle.3mf

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due to the lack of reference images, kunai is not perfect feel free to send good reference image