Spinning Maker Coin

Summary

This sleek, spinning,  seven-pronged maker coin is not only a filament swatch but also a fun-looking fidget that looks great on any desk! With a 6cm diameter and 1.25cm height, this print-in-place geometry prints quickly and requires no assembly. Engineered for ergonomics, the coin’s outer cutout dimensions have been optimized to fit perfectly into a human hand. Then, simply pinch the centerpiece on top and bottom, and it turns into a fidget spinner!

Lesson Plan & Activity

Create a 3D-printed coin that acts as a physical logo/ calling card.

Design constraints were as follows:

• All coins must be made from an initial revolve resulting in a coin that is 6cm in diameter and 1.25cm in thickness.
• Must not require ANY supports.
• Should be gear-esque in nature.
• Must slope downwards towards the center in some fashion.
• Must incorporate EITHER multi-color technology OR print-in-place moveable parts

Overview & Background

There were two overarching design goals from ideation to reality: Make it fit in my hand, and make it spin. Looking through other students’ maker coins, I found that my favorites were those with gears that fit in my fingers. Through experimentation with sketching and digital calipers to measure the dimensions of my fingers, I found that in the given footprint, seven “cutouts” would fit my fingers sufficiently. From there, I filled in the inside of the coin. Looking at others’ designs, I found that those that prioritized simplistic designs and had lots of depth were the most successful. Additionally, some designs that looked awesome in Solidworks ended up printing underwhelmingly due to too much fine detail and not enough depth, resulting in the design not coming through in the final product. Given that I was basing the design off of a circular revolve and relatively-circular/organic finger cutouts, I wanted to prioritize curves in the design. This led to a “weave” idea that connected the finger nodes together. This left a gap in the center of the design, which I decided could be filled by a spinning centerpiece that would “grow” out of the base. Initially, this would be seven-sided such that it would match the outer design. 

• I took inspiration primarily from these other maker coins:
  • • Manakame Maker Coin – This coin made great use of negative space, and I liked the unusual structure combined with its simplicity. In person, this design looked great.
  • • Tessier Maker Coin – This coin utilized lots of different revolves and cuts to create layers, which made the print look super cool despite the actual design being pretty simple. 

• • Visible in this sketch is the web structure that makes its way, practically in this form, into the final design. 
• • This side-view shows the original view for the “growing” centerpiece and the print-in-place spinning geometry.

Design Choices

1. Cutout Sizes

• In the initial sketch, I measured the diameter of a finger to be 16.5mm; however, when I transferred these measurements into Solidworks, the cutouts appeared far too small. This was likely due to the fact that I assumed a consistent diameter in the sketches but ended up freehanding the actual cutout. As a result, the perfect circles in Solidworks appeared too small. 
• As a result, I re-measured my fingers and used an ellipse shape instead of a circle, which produced better-sized cutouts. It is immediately evident from the revised version that these cutouts were more properly sized. 

2. Silhouette Changes

• In the initial design, I assumed that I would have a “lower level” with the finger-fitting cutouts, and an upper level with the web design. On paper, where the intricacies of such a design were not considered, I thought it looked fine: 
• However, as I modeled the object in Solidworks, I was unhappy with how the cutouts clashed with the webs and made the top-down silhouette of the coin look bulky, while my intention was to have the web shape be reflected in the design from all angles. 
• As a result, I took inspiration from Mr. Tessier’s maker coin, which utilized lots of layered revolves and cuts around the outside in order to create a more complex silhouette.
• Implementing a similar idea, I cut out the space in between the “prongs” and filled it with a hexagon and a revolved circular profile. This was a balancing act between making the web/prong structure stick out and still maintaining an outermost point at the troughs of the finger cuts consistent with the original shape such that the finger would still fit. Furthermore, I wanted to introduce some more interesting geometries while not making details too fine such that they would come out muddled from the printer. Additionally, I had to maintain a consistent “solid body” at the bottom in order to make the spinning print-in-place idea work.
• Overall, this update to the silhouette of the coin is effective in highlighting the web/prong structure, which is the focal point of the coin, while still maintaining the functionality of holding the fingers.

3. Centerpiece Changes

• From the start of the design process, I wanted a spinning print-in-place design with a spinning centerpiece that appeared to “grow out” of the middle. However, in the sketching process, I did not think much about what the profile of this piece would look like in the context of the coin.
• In the first Solidworks iteration of this component, I used a seven-sided polygon as the top profile to reflect the seven-sided theme present throughout the rest of the coin. I also made the height of the middle section equal the maximum height of the outer section of the coin, as planned in the sketch.
• I was quite unhappy with how this turned out in the model, as it clashed with the design language present throughout the rest of the model. To attempt to make it blend in more, I first lowered the height of the centerpiece.
• However, I still found the design too cluttered. As a result, I played around with polygons of fewer sides, and eventually settled on five as an amount that did not appear too simple but would come out better from the printer.
• For the final version, I added swept cuts and circular patterned them, then added some revolve cuts to make the top look more interesting. While I am pretty happy with this version and I think it fits in well enough with the rest of the design, in a future version, this would probably be where I would start with changes. 

4. Color Changes

• While the color of the coin is practically a non-issue, as one of the purposes of a maker coin is to serve as a test-print for different filaments, I did make some changes in what filaments I printed in order to bring out more of the design.
  • My first iteration of the coloring utilized a sparkly black/purple filament on the outside, and just a solid black filament on the inside. While I was happy with how it looked, I also wanted to have a very contrast-y option that emphasized the difference between the two pieces. 
  • For the next version, I wanted to make the curves of the design super visible, so I chose a reflective white filament for the outside. This allows the web to really pop out at the viewer. Then, for the inner section, I chose a bold contrasting color, in this case orange, to emphasize the two different pieces in the design. Ultimately, while neither of these color choices is “better” than the other, I do think that the white and orange colorway does a better job of highlighting what makes the coin special. I also think it’s cool that, from the top, the orange piece is visible through the webs.
  • While both of these options were cool, I still thought that the webs did not stick out enough. As a result, I created a final version, which has a three color design that makes the webs pop out much more.

5. Print-in-place Offset Changes

• In order to make the spinning print in place geometry function, I copied dimensions from Simon Jenner’s maker coin, in which he experimented with multiple different spacings to achieve an optimal spinning maker coin. This spacing was 1mm. While the first prints of the design did function as intended with the print-in-place structure allowing a fidget spinner-like motion, the pieces were somewhat loose, resulting in some unsatisfying spinning. This was likely due to the fact that the web structure as well as the ribs on the middle piece had an uneven contact surface. Additionally, I was printing on a Bambu P1S, which allowed for significantly tighter tolerances than the old printers used for Simon’s maker coin, so the optimal spacing was likely different. 
• As a result, for the last version, I somewhat arbitrarily decreased the offset between the two pieces to 0.5mm, which resulted in a tight fit and a more satisfying spin.
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