Ebony and Ivory

This story begins in September 2023. At the time, I designed this necklace for the Jewelry Contest. Back then, I didn't own a 3D printer, so I crafted it out of Solid Surface (an acrylic-based mineral composite). It turned out to be an incredibly complex, tool-heavy undertaking, which is why I never published it. However, three months ago, I finally got a 3D printer, which significantly simplified the entire fabrication process. Now, it’s much easier for you, the reader, to create your own version. This guide covers the evolution of this project over the last two and a half years.

- Tinkercad and Fusion 360 (Design software)

- 3D printer

- Black and white filament

- 2 mm drill bit (for cleaning the holes)

- Elastic hat cord (110 centimeter)

- Deburring tool

Designing a necklace can range from a simple creative exercise to high-precision jewelry engineering. From home-made crafts to professional jewelry design, the result can be a simple accessory or a highly complex, unique work of art. The key is that the final piece should reflect the wearer's personality.

According to Wikipedia:

"Necklaces are typically classified by length:

Collar: A collar is about 30 cm (12 in) to 33 cm (13 in) long and sits high on the neck.

Choker: A close-fitting, short necklace, 35 cm (14 in) to 41 cm (16 in) long.

Princess necklace: 45 cm (18 in) to 50 cm (20 in) long.

Matinee necklace: 56 cm (22 in) to 58 cm (23 in) long.

Opera necklace: 75 cm (30 in) to 90 cm (35 in) long and sits at the breastbone.

Rope necklace: Any necklace longer than opera length.

Lariat: A very long variation on the rope, without a clasp, often worn draped multiple times around the neck."

I designed a Collar-style necklace but scaled it to the length of a Princess necklace. I chose this specific size because the proportional reduction of the piano keys demanded it. If the necklace is shorter, the keys become too tiny; if it's longer, they feel awkwardly large. If I change the number of keys, the "taper" (the spread of the keys) becomes too extreme. To create an accurate model, I needed to research the standard parameters of a piano keyboard.

According to Wikipedia:

„In a typical keyboard layout, black note keys have uniform width, and white note keys have uniform width and uniform spacing at the front of the keyboard. In the larger gaps between the black keys, the width of the natural notes C, D and E differ slightly from the width of keys F, G, A and B. This allows close to uniform spacing of 12 keys per octave while maintaining uniformity of seven "natural" keys per octave.

Over the last three hundred years, the octave span distance found on historical keyboard instruments (organs, virginals, clavichords, harpsichords, and pianos) has ranged from as little as 125 mm (4.9 in) to as much as 170 mm (6.7 in). Modern piano keyboards ordinarily have an octave span of 164–165 mm (6.46–6.50 in), resulting in the width of black keys averaging 13.7 mm (0.54 in) and white keys about 23.5 mm (0.93 in) at the base, disregarding space between keys.”

I used Tinkercad to visualize the final look. Based on the data, I set the ratio of the first two keys to 1/3 and the back two to 1/4, with the keys in between scaling proportionally. I have documented this step-by-step process in the attached PDF. In case any student or teacher feels like trying out these adjustments.

Why choose Solid Surface? It can be machined with the same tools as hardwood, which were already at my disposal. Beyond that, it’s skin-friendly, non-porous, and hypoallergenic. But most importantly: I had plenty of remnants in the workshop.

I used 6 mm material for the white keys and 10 mm for the black ones. I set my table saw’s miter gauge to 2.5 degrees and the rip fence to the width of the widest key. I began the "slicing" process, flipping the Solid Surface sheet along its longitudinal axis after every single cut. (This process is clearly visible in the uploaded images. In one, you can see a line on the Solid Surface sheet and a gap at the rip fence. Following the rotation, these are no longer visible in the second image.) When arranged, these pieces follow each other with a cumulative 5-degree taper.

To establish the precise lengths, I constructed a specialized jig from scrap particle board, featuring a 2.5-degree rabbet cut along its long edge. By arranging the keys face-to-face in a sequence, I was able to size the particle board base accordingly. On one edge (perpendicular to the long edge), I marked the dimension of the shortest key (sitting at the nape), and on the opposite edge, the longest key (sitting on the chest). I joined the two marks with a line and cut the particle board to the required angle. I then fastened cleats to the marked edges and ripped the rear edge parallel to the front. I produced a similar template for the black (sharp) keys as well.

Following this, I made six more templates to rout out the pockets for the sharp keys in the natural keys using a plunge router.. Finally, the project required drilling 244 precisely indexed holes for the elastic cords, plus two dedicated cavities for hiding the knots. Let’s face it: for most people, this level of manual precision would be a "Mission Impossible."

This version requires much more precise engineering because I don't just need a visual model, but functional, printable parts. So I used Fusion 360, a software I recently learned to use, to redesign it.

This resulted in a keyboard with much smoother lines. The curves flow evenly and are no longer composed of segments that break the front faces of the naturals. I tapered the sharps upwards (from the top line of the white keys) and added the characteristic rounding to their fronts. Most importantly, I added serial numbers to the underside of every part to ensure the correct assembly sequence.

In the preparation phase on the toolbar, I imported the model created in Fusion 360 using the 'Import Model' button, using the 3MF format. I opened it as a single object, so instead of a messy pile, I could load the chain neatly laid out. I used the 'Place on Face' (or Lay Flat) function to set it on the build plate, numbers facing up. I then split the object into parts, chose the auto-arrange function, and sliced it.

I wasn’t satisfied with the initial result. I felt the infill was unnecessary, and the direction of the layer lines was disorganized. Therefore, I made the following changes: I manually aligned every single key in the same direction on the build plate so that the print lines would run uniformly. Thanks to this, they fit even on a 200×200 mm bed, making the project reproducible on smaller printers as well.

In the printer selection window, besides setting the parameters for my printer and nozzle, I modified the layer height to 0.12 mm. I set the infill to 0% and the 'internal solid infill pattern' to Concentric. This way, the printer bridges the internal gaps without any infill. I changed the 'Ironing type' to 'Topmost surface' with a 'Rectilinear pattern'. This ensures the ironing happens in a back-and-forth motion and only on the very top layer, saving time. Some might consider this an unnecessary step since the base of the keys rests against our body and isn't visible. However, I believe a piece of jewelry should be as beautiful as possible, which is why I use this feature. On top of everything, it also makes the numbering much easier to read.

I have uploaded the arranged files of the necklace to MakerWorld. If you like my work, please support me with a Rocket (Boost)!

I have been following 3D printing since the birth of the RepRap project. I always wanted to build one, but back then, the assembly and calibration were far more complex than with today’s modern machines, so it never came to be. Thanks to many persistent hobbyists, the technology has become much more accessible, so I took the easier path and purchased one—officially as a gift for my child.

Like our fathers once did with their electric trains, I gaze at the dance of the print head with the same childlike awe, accompanied by the melodies of the stepper motors. It is like the crackle of a vinyl record; the soul of the technology speaks through it. There is something hypnotic about watching physical reality emerge from nothing, layer by layer. I would like to share the experiences I gathered during this process—it might be obvious to some, but for me, it was a revelation.

First, I only performed a test print of four keys, which went flawlessly. Then, I began printing a set of 72 white keys. During the process, I noticed a large blob accumulating on the side of the nozzle, threatening to drop off at any moment. I paused the print; most machines move the head aside in such cases, allowing me to quickly remove the sticky mass from the hot nozzle. After clicking Resume, the machine continued exactly where it had left off.

There is an automated solution for this: the Nozzle Wiper. Some modern printers feature a fixed silicone pad at the edge of the bed where the machine performs the cleaning itself. I will need to set this up in the future.

Later on, I noticed a lot of stringing and some clumping during the print. My concern was groundless, as the hot nozzle (running at over 200°C) continuously passes over previous imperfections when printing the next layers, remelting them and pressing them into the new layer. Of course, some material can stick to the nozzle and form blobs, which is why periodic cleaning is essential.

The next discouraging sight was the printing of the bridges: they initially sagged. Fortunately, my fear was misplaced here as well. When a bridge is printed, the filament is still hot and plastic, and gravity pulls it down. However, as the temperature drops from the printing heat to the ambient temperature, the material wants to shrink. Since both ends of the bridge are firmly attached to the rest of the model, the material cannot shorten, creating internal tension. This tension eventually pulls it straight, like a tightened string.

Encouraged by the success of the white keys, I set out to print the 51 black keys. However, my confidence faltered when I heard a faint, scratchy sound cutting through the melody of the motors. Looking into the printer chamber, I was greeted by a "spaghetti factory"—several keys had tipped over. I stopped the print and cleared the bed.

In the slicer, I added a 5 mm brim (specifically the "mouse ear" type) and restarted the process. This time, the parts stayed firmly in place. However, removing the brim afterwards was time-consuming, and it left the surface finish unacceptably rough.

Third attempt. In the slicer, I flipped the keys so the lettered side faced down, and I set a smaller, 2 mm brim to be safe. The letters are tiny, and I feared they would be illegible. Back to the printer. The result was just right: the keys didn't tip, the letters remained readable, and the brims could be snapped off with a fingernail. Although the edges of the ironing were slightly jagged, they are easily corrected with a bit of post-processing. For this, I used a sheet of coarse paper laid on a table, moving the slightly tilted key back and forth with quick motions (as if sanding).

First and foremost, I looked for some pleasant, keyboard-heavy music – just to stay in style. The keys are marked with numbers and letters to make the stringing process easier. The markings are as follows: recessed numbers from 1 to 36 on one side, and numbers in a circular field from 1 to 36 on the other. Lowercase letters of the alphabet are located on one side, while uppercase letters are on the other. I arranged the keys with their marked sides facing up so that I wouldn't have to search for them later.

I took the elastic hat cord, heated the two ends with a lighter, and shaped them into points to make it easier to thread them into the holes. Then, I folded the cord in half and began stringing the keys by passing it through both holes simultaneously. Two holes are necessary to prevent the keys from wobbling or tangling.

The sequence of the first elements is: Circle 35 (this one features a cavity for hiding the knots of the hat cord), Y, Circle 36, Z, 36, y, 35, x, 34, w, and so on, until I went all the way around. I aligned the keys, keeping the cord loose, then placed a spacer into the starting loop so that the other two ends of the cord could be easily threaded through. I slightly tensioned the strands and marked them with a fine-tip felt-pen.

I pulled both ends of the cord simultaneously, and after threading them through the raised loop, I tied a sliding knot on each, mirror-symmetrically to one another. The mark previously drawn with the felt-pen must end up exactly inside the knot to ensure the keys close tightly. Finally, I tied the two ends together – which face each other thanks to the symmetrical knots – using a figure-eight knot. I cut off the excess and sealed the frayed ends of the cord with a lighter.

The finished necklace possesses a remarkably powerful, almost monumental aesthetic. Its form echoes the ornate breastplates of Mayan culture and the majestic jewelry of ancient Egypt—reminiscent of the striking pieces often seen in modern superhero movies. Given its bold presence, it is not intended for casual daily wear; however, as a statement piece for a costume, it is unparalleled. It pairs exceptionally well with the top hat I previously designed. Combined with a mandarin collar suit, a slender cane resembling a conductor's baton, a treble clef brooch, and a tousled hairstyle, one can easily embody a new 'The Music Meister' type supervillain character.

However, the concept offers more versatility than just a single grandiose piece. For a more understated look, one can use only the 17 central keys that rest on the chest. This shorter sequence functions as a modern pendant, perfectly suited to enhance everyday elegance.

For the tech-savvy makers, I have developed a version where a 10 mm circular NFC tag can be hidden inside the white keys. By inserting a pause in the print at layer 16, the chip can be embedded before the machine seals the part. This transforms the jewelry into a functional smart device, whether for sharing digital business cards or storing secret messages. Furthermore, if you have a compact NFC reader, the necklace can even serve as a unique, "invisible" musical instrument.

I hope this project has sparked your imagination. Download it, customize it to your heart's content, but most importantly: have fun with it!

Based on the feedback regarding the scale and versatility, I’ve designed a new, "lighter" version of the model. This variant consists of 17 keys and is significantly flatter, making it perfect to use as a pendant or to combine with other jewelry beads.

Key dimensions:

White keys: 4 mm height

Black keys: 6.5 mm height