I've been looking around a little, and I couldn't find anything about douk-douks that have been customized, either with different handles, handle engraving, blade engraving, or re-ground blades. After what I've seen of the custom Opinel scene I was a bit surprised. I suppose douk-douks are nowhere near as popular as Opinels, but they seem like they would be a lot of fun to play around with customizing, in many different ways. For starters, although that blade shape is highly unique and interesting (and attention-grabbing), it isn't all that aesthetically pleasing (to me, anyway), and it seems like there would be some demand for douk-douks that have had their "Turkish clip" ground off, turning them into a regular clip-point blade (shaped something like the blade of a Stockman slipjoint). I suppose the presence of the etched arabesques on the standard "Douk-Douk" knife would make this difficult, but you can easily find models with blank blades, like the El Baraka.
The possibilities are endless; made a clip point, like I mentioned. Grind off the redundant hump on the spine and make it into a plain "scimitar" blade, instead of the weird "clip-point/scimitar blade" they went with (I still can't fathom why exactly). One could sharpen the spine behind the tip, making either a false edge, or even a true edge; this would work whether you retained the scimitar point or went with the clip-point. This would greatly improve the stabbing/puncturing performance, which cannot be very great considering the stock tip geometry. I hear these tales of assassins and rebels using douk-douks as "daggers" by hammering the bolsters shut (exaggerated tales I suspect), but I can't imagine they would make ideal combat knives with that big, blunt-edged, almost vertical Turkish clip rising up right behind the tip.
While I'm here I also suspect that the so-called "bail" or "lanyard loop" is actually intended to serve primarily as a blade safety catch. If they wanted to attach a lanyard, all they needed to do was punch a hole in the heel of the handle. Instead they add this piece which brings the part count up from 4 parts to 6 parts. An entire rivet and bail that could be replaced with a pair of small holes? But I've noticed that if you flip the "bail" back over the blade when it's folded, it is impossible to open the blade up. The same is true on all counts for the Mercator K55K. Not sure why a knife with a spring as powerful as the douk-douk would need a safety catch to hold it shut, but perhaps the spring has changed over the years, or the knife loosens up as it wears. The K55K has far more need of a safety catch than the douk-douk. You will note that the other knife in the trio, the higonokami, makes do with a single rivet and a hole punched in the heel of the bolster. It features only 5 parts, if you count the two brass washers as 2 parts.
The possibilities are endless; made a clip point, like I mentioned. Grind off the redundant hump on the spine and make it into a plain "scimitar" blade, instead of the weird "clip-point/scimitar blade" they went with (I still can't fathom why exactly). One could sharpen the spine behind the tip, making either a false edge, or even a true edge; this would work whether you retained the scimitar point or went with the clip-point. This would greatly improve the stabbing/puncturing performance, which cannot be very great considering the stock tip geometry. I hear these tales of assassins and rebels using douk-douks as "daggers" by hammering the bolsters shut (exaggerated tales I suspect), but I can't imagine they would make ideal combat knives with that big, blunt-edged, almost vertical Turkish clip rising up right behind the tip.
While I'm here I also suspect that the so-called "bail" or "lanyard loop" is actually intended to serve primarily as a blade safety catch. If they wanted to attach a lanyard, all they needed to do was punch a hole in the heel of the handle. Instead they add this piece which brings the part count up from 4 parts to 6 parts. An entire rivet and bail that could be replaced with a pair of small holes? But I've noticed that if you flip the "bail" back over the blade when it's folded, it is impossible to open the blade up. The same is true on all counts for the Mercator K55K. Not sure why a knife with a spring as powerful as the douk-douk would need a safety catch to hold it shut, but perhaps the spring has changed over the years, or the knife loosens up as it wears. The K55K has far more need of a safety catch than the douk-douk. You will note that the other knife in the trio, the higonokami, makes do with a single rivet and a hole punched in the heel of the bolster. It features only 5 parts, if you count the two brass washers as 2 parts.