The following tutorial is courtesy of Bill Doran from Punished Pixels at http://props.punishedpixels.com/2013/04/02/darker-than-black-heis-daggers/
A couple of months ago I got my hands on a commission to build Hei’s Daggers from the anime show Darker than Black. Fortunately for me, my pal Harrison from Volpin Props had already made the dagger and has blueprints available for an insanely low price of $5. Having the blueprints already done usually saves me 1-2 days of research and drawing. I have my own blueprints available for sale here!
I printed up the designs full scale and got started! My plan for this was pretty similar to the way that Harrison built it. I planned out several layers of PVC sheet and styrene in different thicknesses.
Most of the pieces were cut out with an X-Acto knife. Some of the thicker parts were cut out with my scroll saw. The layers were all epoxied together.
The beveled edges on the side of the dagger were filled in with Bondo. I also added more styrene to the blade tips to reinforce them.
Once it was all filled in and sanded down, I got it all primed up and did some more sanding.
At this point, it was all ready for molding! Originally I thought I would need to cast it with some steel wire inside of the plastic for strength. This actually made the blades bow quite a bit, so I tried casting one without the wire. The non wire blade casting was incredibly durable and didn’t bow at all!
The finished blades were cast from SmoothCast 300 with a little bit of SoStrong black tint.
With the pieces all cast, they needed just a little bit of sanding and some paint! The base color was a rattle can metallic paint. Then I masked off the edges of the blade to paint the rest of it black.
After some clear coating, I did some light touch up weathering with a dry brushed black paint and some silver leaf Rub ‘N Buff.
That’s it! All done! Nothing to see down here!