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The process of making double shot keycaps

We wanted to publish this article and give everyone an insider's look into the incredibly interesting process of making the colorful plastic that we all love: keycaps. Step 1: Designs and Inspiration You may know from your favorite designers like Matt3o, MiTo, Oblotzky, T0mb3ry, and Cassidoo that design inspiration doesn't just happen, it needs to be nurtured.  These designers spend hundreds of hours thinking about concepts, developing them, scrapping and iterating to find the right theme that will grace thousands of keyboards. There are a ton of constraints that these professionals need to consider when thinking about their designs.  Beyond obvious aesthetic issues like colors and fonts, careful consideration like keycap profiles, extended board compatibility, multilingual legends and physical materials regularly come into play. After all this, 3-dimensional renders need to be produced using CAD software to help fans visualize the product that we intend to bring to market. Step 2: Color Sampling and Tooling For double-shot keycaps, special "tools" need to be made.  Loosely defined, a tool is a metal mold that molten plastic is injected into to take the form of the tool.  For double-shot plastic keycaps, every single legend (i.e. the character "F") needs a specific tool to be made to make the character.  As seasoned veterans know, many of the “alpha legends” (i.e. A, B, C) tools are reused across different keycap sets with different colored plastic injected each time.  However for novelty keycaps, each novelty design needs its very own tool. Tools are often not a "one and done" process.  After an initial tool is made, sample keycaps are produced, and then the tool may be altered or remade in order to correct nuances that need adjustments.  An example is that some characters may have lines that are too narrow, or too thick.  It's important to realize that tools and plastic exist in the physical world, compared to the digital world of "pixel perfect renders".  Plastic expands and contracts at different temperatures, so the hot (molten) plastic that takes the impression of the tool will always shrink a little when it hardens and cools.  This is why the actual tool and resulting plastic legend will never be physically identical to the render.  Higher quality tools and higher precision manufacturing processes will result in a closer, but not exact match.  To make things even more complicated, tools are generally material-specific, so if your tools are initially made with ABS plastic, you can’t just switch it to PBT plastic- new tools need to be made! To further complicate things is the issue that bi-colored keycaps are "double-shot" which means a single color (typically the legend) is first formed, and then a second color (the surrounding keycap) is injected and formed around it.  This creates additional complexity because adding molten-hot plastic to hardened plastic leads to slight melting and deformation of the original plastic.  So that legend you so carefully calibrated in phase 1, can quickly become a hot-mess after the second part of the "double shot" process. The following is a rare photo of our MT3 Doubleshot process, which depicts the singleshot legends (light colored, on the left), followed by the finished keycap when the exterior (red and grey) is formed around it.  For keys that have a non-continuous exterior color, i.e. Q pictured below, there needs to be a special hole drilled into the base legend so that we can inject additional plastic to fill the hole.  These are called “islands” and some keys have multiple islands.
Each keycap requires its own tool to be made, and each tool needs to be carefully calibrated.  With most base kits having 120+ distinct keycaps, that’s a lot of work! While it would be nice to say that all of this can be automated, it simply cannot.  Like a fine wine vintner- manufacturing experts are constantly monitoring tons of variables to make sure everything is just right.  Resin temperatures, injection pressures, tool calibrations are all required to make sure that everything is running at an "optimal" level.  Quality control is obviously required to try and catch the occasional deformed keycap that comes out of the production machines.  Despite all of this, we definitely have some keycaps that don’t quite make the cut and they slip past quality control.  In these cases, please don’t get angry, just let us know and we’ll happily replace it.  Below is a photo of a "2@" key where you can see an injection defect, ultimately the plastic of the second shot didn’t quite fill the entire mold.

"Just make it more purple" With tooling and production issues mentioned above, another absolutely crucial issue is the color of the resin used for the keycap (or legend).  Contrary to most people’s assumptions, the plastic (resin) is not made at or by the keycap factory, it’s made at a separate factory that specializes in making very specific colored plastic.  Making colorful plastic is an extremely complicated and delicate science and once again, is drastically different from the digital world. Large batches of resin need to be mixed in order to properly run through an injection molding machine (can’t just make a gallon of it and call it a day), and if the colors don’t look quite right, the process needs to be repeated.  Sending feedback to the resin manufacturer and having them make a new batch, and transporting that to the factory, is a process that typically takes weeks.  Not only that, but each time a color sample is struck from a keycap machine, if we want to sample a different color, the entire machine needs to be flushed clean of the old resin otherwise the colors will get contaminated. Another important concept to note is that plastic colors will appear to be different depending on their environment or background.  A “sample chip” of purple will look considerably darker (or lighter) when that sample purple resin has been injected into a black (or white) keycap enclosure.  This is why purely working off of Pantones (or other solid color samples) isn’t perfect, because the colors independently may look great, but when used as a stenciled keycap legend, the perception of the color changes drastically. This is particularly true if you compare a physical product to an image on a monitor, as the color interactions are drastically different. For these reasons, the color matching and tooling process is by far the most time consuming process when making custom keycaps- and it typically takes many months (sometimes over a year…).  It’s also the primary reason for delays with keycap production, because we’d rather “get it right” than “just get it done”.  While we generally budget time for 3-5 sample runs, we occasionally end up needing 10 sample runs which ultimately results in 5 months of delays. Step 3: Production Once the tooling is set and the resin colors are determined we can move into the production stage.  Depending on the size of the run, the production portion takes anywhere from 1-4 weeks for a typical keycap order of thousands of kits.  Most people think of the production phase as being the major bottleneck but as discussed above, it typically isn’t!  Also, to contrast the efficiency difference, most mass produced keyboard brands have spent 6 months working through calibrating Step 2, and then spend years producing the same lifeless keycaps all day every day. With the custom sets that enthusiasts are used to, 5 months is spent calibrating, and only 1 month is spent in production, and then the whole process repeats itself! Step 4: Packaging We wish there was a machine that put keycaps into trays or bags for us, but at these levels of production it isn’t economically feasible.  Packaging of keycaps is a slow and manual process that simply involves human beings grabbing them and placing them in QWERTY order into their slots and gently sealing the packaging.  There is room for human error here, which is why the occasional keycap set may be missing the “J” key or have a second 9 instead of a 6-key.  Packaging does give us an extra opportunity to run quality control and have a final set of eyes on every keycap before it ships. Step 5: Shipping Bulk orders are shipped to our warehouse via airplane cargo (ocean liners take ~6 weeks).  Each keycap set is counted, unloaded, and shelved.  It’s then ready to be picked, packed and shipped to you! We hope this write-up gave you some interesting insight into the keycap production process. If you have any questions, leave a comment below!

Mar 15, 2022
How is kitting done? Is there a way that the community can more clearly communicate the kitting needs? I understand the molds have been made, but for future iterations is there a way that the kits could be defined to better fit the needs of the customer? @MiTo did a great job surveying the community and did things like including an R2 backslash-pipe key for 5x15 ortho layouts. I've bought 4 figures (easily) of MT3 Godspeed based on the proper support and kitting. Just copy GMK's lead and offering combo and discrete kitting that way would make more sense than the frustrating coverage of MT3's kits. Even just make blank sets!
Oct 13, 2020
Very interesting article! I work in plastic pipefitting manufacturing, so I know about injection molding, but to see it specifically for keycaps is wonderful. I always wondered how the doubleshot mold happens, and seeing that the character is raised in the first shot makes it make sense to me.
Oct 13, 2020
Enjoyable, informative read. If only your product page copy was crafted with a fraction as much care and attention to detail. One can only hope.
Oct 12, 2020
Really cool article! You're doing a great job! Thank you for doing it for us to have a nice keyboards! 💜
Oct 12, 2020
great article! understanding the process is part of the procedure!
Sep 14, 2020
Wow, I did not know that it was this complicated to design, created and then distribute key caps. Thank you for sharing the hard work!
Sep 14, 2020
this was super interesting! i've always enjoyed looking at the underside of my doubleshot caps – that criss-crossy pattern of the legend colour for strength and so forth. and of course, knowing all this makes extra sense as to why my DSA pulse's 5 keystem kept coming off, since % needs two little islands fitted in amongst the underside stripes! (as i recall, my replcement 5 keycap actually came from SP even tho the rest of the set didn't, so i guess the chinese manufacturer kept ending up with a brittle final product? although it's interesting that 3 and 7 were fine, since "#" and "&" have tiny islands too, "&" even having two of 'em just like "%")
Sep 12, 2020
Excellent article with some fascinating insights into the keycap manufacturing process. Thank you for preparing this piece. <3 I'm now going to go and look carefully at my still-in-the-box MT3 Susuwatari set to see if any human/production errors made it into my package. XD
Sep 12, 2020
After reading about the process I am now amazed any keyset ever gets done!
Neat! I was always curious about the process
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