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Fully built
Good to know: Keyboard sizes and layoutsHot-swap keyboards
The MMD KM40 is for anyone who has ever wondered what a 40% keyboard actually feels like — and for anyone looking for a compact, well-made secondary keyboard for travel, office, or setup variety. Instead of overpriced custom builds or cheap plastic competitors, the KM40 gives you a CNC aluminum case, O-ring gasket mounting, hot-swap PCB, tri-mode wireless, MMD Princess Linear Ultra Switches and full QMK/VIA support — all at a price that makes entering the 40% world surprisingly accessible. A thoughtful package, not an over-the-top enthusiast board.
If you've never worked with a 40% keyboard, you might be confused at first: Where are the number keys? The F-row? The arrow keys? The answer: all keys are still usable, but they live on layers. Think of it like the Shift key — when you hold Shift, "a" becomes "A". On the KM40, you hold the Fn key, and the letter row becomes the number row, other keys become arrow keys, F-keys, and special keys.
The advantage: your hands barely have to move. Instead of reaching for the distant arrow key, you stay in the home row and use a layer. After a short adaptation period, this makes 40% surprisingly efficient — especially for programmers, Vim users, and anyone who appreciates fast, focused typing. The KM40 supports 10 layers with up to 430 programmable key values — you can configure your 40% world entirely to your needs.
We'd also like to take this opportunity to introduce you to the 40% Keyboard Community — there you'll find not only a great Discord community but also lots of helpful resources in the wiki!
MMD didn't cut corners on the case: it's made from CNC-machined 6063 aluminum — the same material standard you'll find in significantly more expensive custom boards. Depending on the color variant, the surface is either anodized or electrophoretically coated, ensuring consistently high-quality haptics and color depth. The substantial aluminum not only gives the KM40 a premium feel in your hand — it also provides stable footing and acoustic resonance.
Inside, the KM40 uses an O-ring gasket structure that delivers a soft, bouncy, and acoustically dampened typing feel. Rattling resonances and hard bottom-outs are minimized. Additionally, MMD includes Poron and IXPE sound dampening materials in the case — a combination typically found in significantly more expensive boards, ensuring a clean, defined sound profile.
The KM40 is fully hot-swappable — you can swap all 44 switches without a soldering iron, perfect for sampling and experimenting. The PCB is QMK/VIA compatible, which means:
Especially with the 40% layout, this customizability isn't a luxury but essential: every user has different requirements for which keys should live on which layers.
The KM40 connects three ways:
Via the hardware mode switch, you seamlessly switch between connection types. The 2000 mAh battery ensures long wireless sessions, charging is via USB-C — and the keyboard is fully usable while charging.
The included keycaps are 1.7 mm thick five-sided dye-sub PBT keycaps — a material quality typically only found at significantly higher price points. Thanks to dye-sublimation, the legends are permanently anchored in the material and won't wear off. The thick material guarantees a fuller typing feel and acoustic depth.
The KM40 features RGB backlighting with 22 pre-programmed effects and 16 million colors. You can fine-tune brightness, mode, and colors either directly via key combinations or through VIA — from a subtle, single-color glow to a dynamic, animated light show.
With dimensions of just 235 × 85 × 20–28 mm and a weight of around 620 g, the KM40 is exceptionally compact and mobile. It fits in any laptop bag, any backpack, and even in many handbags — ideal for commuters, travelers, or as a space-saving secondary keyboard on the desk.
To set the right expectations: the KM40 is not a custom build in the premium segment. It's a thoughtful, well-made entry-/mid-range build with excellent value for money. If you're looking for a 40% keyboard with FR4 plate options, swappable bottom weights, or similar custom-build features, you'll find other models with us. If, however, you're looking for a serious, well-made 40% keyboard without the premium markup, the KM40 is an excellent choice.
Fantastic little 40%. Well built. Surprisingly solid switches and keycaps. Excellent value. Delivery was fast and flawless.
Needed to find a VIA .json file online and edit it with an AI chatbot to configure it as I wanted but it was easy enough.
Cool little keyboard
A 40% keyboard requires some dedication, but the customisation possibilities of this keyboard make it really flexible and adaptable. The materials and finish are pretty high-end, and the switches give a very satisfying feel. The RGB effects add a nice touch.
A really nice little 40% keyboard
A really nice little 40% keyboard, deserves 5/5.
40% layout will definitely require some time to get used to :)
Can only recommend the shop, they do care about customers.
Cute little Keeb
I’d been wanting a 40% keyboard for a while, but I just didn’t want to spend €200–300 on something I’d only use every now and then. At €85, what’s the worst that could happen? And I wasn’t disappointed. The switches and keycaps sound and feel very high-quality. The case is also well-built. The small keyboard makes a very nice overall impression that feels worth more than €85.
The key mapping on the FN layer doesn’t make sense to me, but I didn’t expect to be able to start using it right out of the box without making some adjustments. With a 40% layout, you should think about the mapping anyway to achieve the best flow.
The MMD KM40 is for anyone who has ever wondered what a 40% keyboard actually feels like — and for anyone looking for a compact, well-made secondary keyboard for travel, office, or setup variety. Instead of overpriced custom builds or cheap plastic competitors, the KM40 gives you a CNC aluminum case, O-ring gasket mounting, hot-swap PCB, tri-mode wireless, MMD Princess Linear Ultra Switches and full QMK/VIA support — all at a price that makes entering the 40% world surprisingly accessible. A thoughtful package, not an over-the-top enthusiast board.
If you've never worked with a 40% keyboard, you might be confused at first: Where are the number keys? The F-row? The arrow keys? The answer: all keys are still usable, but they live on layers. Think of it like the Shift key — when you hold Shift, "a" becomes "A". On the KM40, you hold the Fn key, and the letter row becomes the number row, other keys become arrow keys, F-keys, and special keys.
The advantage: your hands barely have to move. Instead of reaching for the distant arrow key, you stay in the home row and use a layer. After a short adaptation period, this makes 40% surprisingly efficient — especially for programmers, Vim users, and anyone who appreciates fast, focused typing. The KM40 supports 10 layers with up to 430 programmable key values — you can configure your 40% world entirely to your needs.
We'd also like to take this opportunity to introduce you to the 40% Keyboard Community — there you'll find not only a great Discord community but also lots of helpful resources in the wiki!
MMD didn't cut corners on the case: it's made from CNC-machined 6063 aluminum — the same material standard you'll find in significantly more expensive custom boards. Depending on the color variant, the surface is either anodized or electrophoretically coated, ensuring consistently high-quality haptics and color depth. The substantial aluminum not only gives the KM40 a premium feel in your hand — it also provides stable footing and acoustic resonance.
Inside, the KM40 uses an O-ring gasket structure that delivers a soft, bouncy, and acoustically dampened typing feel. Rattling resonances and hard bottom-outs are minimized. Additionally, MMD includes Poron and IXPE sound dampening materials in the case — a combination typically found in significantly more expensive boards, ensuring a clean, defined sound profile.
The KM40 is fully hot-swappable — you can swap all 44 switches without a soldering iron, perfect for sampling and experimenting. The PCB is QMK/VIA compatible, which means:
Especially with the 40% layout, this customizability isn't a luxury but essential: every user has different requirements for which keys should live on which layers.
The KM40 connects three ways:
Via the hardware mode switch, you seamlessly switch between connection types. The 2000 mAh battery ensures long wireless sessions, charging is via USB-C — and the keyboard is fully usable while charging.
The included keycaps are 1.7 mm thick five-sided dye-sub PBT keycaps — a material quality typically only found at significantly higher price points. Thanks to dye-sublimation, the legends are permanently anchored in the material and won't wear off. The thick material guarantees a fuller typing feel and acoustic depth.
The KM40 features RGB backlighting with 22 pre-programmed effects and 16 million colors. You can fine-tune brightness, mode, and colors either directly via key combinations or through VIA — from a subtle, single-color glow to a dynamic, animated light show.
With dimensions of just 235 × 85 × 20–28 mm and a weight of around 620 g, the KM40 is exceptionally compact and mobile. It fits in any laptop bag, any backpack, and even in many handbags — ideal for commuters, travelers, or as a space-saving secondary keyboard on the desk.
To set the right expectations: the KM40 is not a custom build in the premium segment. It's a thoughtful, well-made entry-/mid-range build with excellent value for money. If you're looking for a 40% keyboard with FR4 plate options, swappable bottom weights, or similar custom-build features, you'll find other models with us. If, however, you're looking for a serious, well-made 40% keyboard without the premium markup, the KM40 is an excellent choice.
Fantastic little 40%. Well built. Surprisingly solid switches and keycaps. Excellent value. Delivery was fast and flawless.
Needed to find a VIA .json file online and edit it with an AI chatbot to configure it as I wanted but it was easy enough.
Cool little keyboard
A 40% keyboard requires some dedication, but the customisation possibilities of this keyboard make it really flexible and adaptable. The materials and finish are pretty high-end, and the switches give a very satisfying feel. The RGB effects add a nice touch.
A really nice little 40% keyboard
A really nice little 40% keyboard, deserves 5/5.
40% layout will definitely require some time to get used to :)
Can only recommend the shop, they do care about customers.
Cute little Keeb
I’d been wanting a 40% keyboard for a while, but I just didn’t want to spend €200–300 on something I’d only use every now and then. At €85, what’s the worst that could happen? And I wasn’t disappointed. The switches and keycaps sound and feel very high-quality. The case is also well-built. The small keyboard makes a very nice overall impression that feels worth more than €85.
The key mapping on the FN layer doesn’t make sense to me, but I didn’t expect to be able to start using it right out of the box without making some adjustments. With a 40% layout, you should think about the mapping anyway to achieve the best flow.
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