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Build materials and other case design considerations

Entry topics: 
▪️ Build Materials and Design Considerations (you are here)
After discussing low-profile and high-profile cases last week, in addition to size/layout and staggered/ortholinear layouts previously, we’ve now arrived at the last of four “intro” topics to cover the basics of mechanical keyboards (not counting the switch topics that ThereminGoat has contributed as well). Our final entry in this initial series is about build materials and other case design considerations. Because there is so much to cover on this topic, some things will be omitted - let us know what you want to see more of in the comments below.    Aspects we will cover: 
▪️ Materials
▪️ Case Construction
▪️ Weights

Plastic vs Metal Broadly speaking, most mechanical keyboards will either be “plastic” or “metal”; of course, the specific plastic or metal of choice will impact how a board feels, but these are the two main categories. Most beginner and/or mass-market keyboards are made of plastic while most boutique or custom boards are metal. After all, if you’re going through the effort of designing and manufacturing a small production run keyboard, why not go all-out on the material? Manufacturing/setup time accounts for most of the unit cost of CNC-milled products anyway.  Most newcomers to the hobby have their eyes set on a nice metal keyboard as a “someday” purchase, and rightly so. The extra weight and premium feel is certainly appealing and an indication of build quality. Keep in mind, however, that the case material has a huge effect on the sound of a keyboard, and in many cases a more basic plastic case can sound better than its metal counterpart without modification.  Metal
Image Credit: @chiefmate

Image Credit: @RobertTho87

Types of Metal
Image Credit: @spacecables

Aluminum By far the most common type of metal used in custom and semi-custom keyboards is aluminum. There are slightly different grades of aluminum used, but you’ll never notice a difference between them. One nice benefit of aluminum is that it can be anodized to a variety of colors, giving a quality finish and appearance that won’t chip off. Aside from anodization, there are a whole host of other finishing techniques that are commonly used when producing keyboards, which will be covered in a future article.  Steel/Titanium Second and third to aluminum (in no particular order - if anyone has actually tracked this, let me know) are steel and titanium. Both are harder to machine than aluminum, and come with their own processing difficulties that make them far more niche than aluminum. Titanium is also expensive, so there’s that too.  Brass The last metal that I’ll mention is brass, and it’s mentioned last because it’s more often used for plates and weights than entire keyboard cases. Brass is very dense, adding a nice heft to otherwise “light” aluminum cases, and the coloring can provide a nice accent as a plate material.  Differentiating between all these materials in terms of pure quality is pretty dicey, since most of it comes down to personal preference. Brass weights are generally considered to be more desired than alternatives, and truthfully I think aluminum has so solidly dominated the case landscape that you’d be hard-pressed to find anything else not on the fringes.  Types of Plastic
Image Credit: @low_key_keyboards Commercially-produced keyboards made of plastic will usually use a proprietary compound that might vary from manufacturer to manufacturer, so I won’t speculate on what those might be (I wouldn’t be surprised if they are ABS or some derivative). Hobbyist keyboards made of plastic, on the other hand, commonly fall into a couple of categories - polycarbonate or acrylic - each with their pros and cons.  Polycarbonate is more flexible than acrylic and can be processed at a thinner thickness, making it a more viable plate option than acrylic (plates need to be pretty thin to allow switches to snap in). If you’re thinking about a plastic plate for your build, polycarb is probably where you’ll end up.  You can build entire keyboards from sheets of either polycarbonate or acrylic though, and that is where acrylic can shine, especially for prototyping. Relatively thin sheets of acrylic can be laser-cut quite easily, and stacked together to form a case complete with plate. If you are soldering your switches into the PCB, the slightly-too-thick plate becomes much less of a problem as the switches will not pop out like they might with a hot-swap socket.  What about Wood?
Image Credit: @perfectd3 Good question. A brief search for wood cases on reddit or other platforms will reveal a fair few handmade wood cases. I’m not aware of a mass-market wood case for mechanical keyboards, but since wood is so easy to cut and process, it’s relatively easy to mill out a tray-style case on a CNC milling machine. I won’t dive too far into this here since it’s a little more obscure as far as purchasing a case goes. Suffice to say that it can be done and it can look amazing.  Case Construction
Image Credit: Layered sandwich, top-mount, bottom-mount, gasket-mount, leaf spring-mount, tray-style. Case construction options seem to be nearly endless, and only get more complicated as the hobby grows.  The most simple case/mounting style is the tray. A cavity is cut out of a block of material, and the PCB with switches and caps is mounted inside of it. This style works best for layouts that don’t have gaps between any grouping of keys. No gaps means no top portion of case to cover blank PCB space and the tray works great.  Most other case designs use two out pieces of some sort, a top and bottom piece. Sometimes the plate is built into one of these pieces, other designs have the plate mounted to either the top or bottom (top-mount and bottom-mount, respectively). At the surface level these design differences are very easy to understand. Personally, I don’t notice a difference between them in terms of typing feel, but I’m sure some do. :) (leave a comment with your preference if you have one)  Layered sandwich cases were alluded to earlier, when discussing acrylic cases. Sheets of plastic, metal, or wood can be bolted together to form a full keyboard case, great for small production runs or in-home prototypes of new layouts or PCBs.  Gasket-mount designs are a relatively new case construction option. Rather than mounting the plate directly to the case with screws or other fasteners, gasket-mount keyboards instead sandwich the plate between an upper and lower “gasket” (usually a squishy foam) positioned on the upper and lower portions of the case. These gaskets hold the plate in position and allow for some flex in the overall structure as the user types on the keyboard. Increased flex is commonly associated with a preferable and more comfortable typing experience.  Newer still is the leaf spring-mount design, taking the flex-seeking aspects of gasket-mount to the next level. Instead of relying on compressing the plate between gaskets to provide a “spring” effect, the PCB or plate is instead mounted to a leaf spring, a bent piece of metal that provides both structural support and substantial flex. The result is a cleaner and more elegant design. Hard mounting points are often preferred over the less precise gasket mount system. Preference is ultimately up to the user though, and I believe leaf spring-mount keyboards are still fairly niche and expensive at this point.  Weights
Image Credit: @Rawdilz As alluded to above, weights are often added to the bottom of metal keyboard cases in order to give a bit of extra heft to the overall keyboard. Brass weights are most common - both adding a more dense material for efficient bonus weight as well as giving a nice accent color in many cases. Aluminum “weights” can also be used as a pop of accent color and design feature, though obviously aluminum in place of aluminum does nothing to add weight to the overall keyboard.  What materials do you prefer for your boards?

Nov 15, 2022
Sorry for the multiple comments. My only issue is me having a hard time finding boards that utilize the 108 key configuration. I'm just a LOT more comfortable with that then the smaller boards.
Dunn.RingillThat is probably the biggest downside to the hobbyist side of things. There isn't a ton of support for fullsize boards. Have you tried an 1800 layout?
Nov 16, 2022
HoffmanMysterThank you. I think my next one will be an 1800 as they are a lot more choices to choose from.
Nov 15, 2022
I never thought I would fall for this, but I have and I am HOOKED. I love collecting these. I make mine as "themes". I color match the keys/board, mat and background on my computer screen. So far I have these themes: (1) Pink Floyd "A Momentary Lapse of Reason" (2) Teenage Mutant Ninja Turtle inspired one (3) Optimus Prime inspired one and (4) one that matches the color scheme of my favorite album of all time ... Jethro Tull's "Crest Of a Knave" release. I think my next will be???
Dunn.RingillHaha, it gets the best of us. Far too easy to fall off the deep end. 😂 You should share your boards! I'm very interested to see the two music inspired builds in particular. Especially Jethro Tull - great band. I'm a bigger fan of their '70s work myself, but you can't go wrong.
Cool article topic.
Pretty cool article!
I'm definitely a brass fan when it comes to weights. I like my board to be nice and hefty. I also like brass plates, but I wouldn't say I'd only go brass.
Nov 29, 2022
MorbiiPersonally my favorite plate material has been dependent on the mounting system. ABS/aluminum for top mount, carbon fiber for bottom mount and brass for gasket mount. This is based on trying out boards with various combos for that long. I can also say that the type of switch is also important on the plate choice as you want to take into account sound in addition to feel. For instance, stiffer plates feel bad on linears and light tactiles, where as you want a firm ring on a sharp clicky switch or a bit less flex for more feedback on heavy tactiles.
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