I think this is what you’re looking for 
Ah, ok I understand. For now, let’s focus on runic alphabets then
Do you by any chance have any insight on whether or not using some of the languages suggested above will result in copyright lawsuit @jesse?
Copyright will not be a problem for runes themselves.
Although I suppose any specific drawing of runes might be copyrighted, the runes themselves vastly pre-date copyright. This would be a situation exactly similar to the alphabet.
For what its worth, there was a set in Elven tongue sold on massdrop, and I know of no cease-and-desist cases.
I figured my edit would be a huge technical limitation to overcome for what might be a minority. 
I’ve seen a lot of proposals, but we’re not seem to reach a consensus.
I’m trying to summarize some opinions:
Yes, I also would like to have runes on all the keys. Possible exceptions can be the butterfly key (as mentioned by @moltendorf).
I like the Hymmnos that @rayzlight is proposing. It is clean, looks modern and does not look like a recognizable alphabet.
Many people seem to like Tengwar. Well, I don’t. I don’t like LOTR, so I also do not like Tengwar. So IMHO the chosen alphabet be the as “political neutral” as possible.
I’ll have a look at Unicode 15.1 Character Code Charts and see if I find something I like.
What would be great is if someone felt like starting to mock up actual images of options using @arley’s SVG template:
Quick & dirty Hymmnos SVG mockup:
download: https://unascribed.com/f/0e4903c4_keyboardio-vector-hymmnos.svg (you need the Hymmnos TTF installed)
I arbitrarily assigned mouse buttons to /> and </, and fn became Xeku, as that symbol looks crazy and seemed fitting for an important modifier key. Blew up some of the black lettering to account for the more detailed font, but got fed up with drilling down into groups in Inkscape around when it came to the red lettering. I apologize in advance for any Hymmnos experts I’ve offended by my gross misuse of the symbols 
Shift became Spag, Tab became… tab? It’s pretty sloppy and is just intended to see what a Hymmnos keyboard could look like. Could use a few more changes especially to special keys to make them no longer use Latin lettering. Some experiments with lowercase Hymmnos could also be useful.
@unascribed I like it!
Although I would prefer a single legend on each cap.
How did you make it? I would like to make one with the Alchemical Symbols ( http://www.alanwood.net/unicode/alchemical-symbols.html ).
I took the pre-existing SVG template and switched some fonts around.
I’d prefer a single legend as well, but I wanted to leave the template mostly unchanged.
Love this thread! Full of great suggestions.
For some reason, when I answered the survey and saw “Unique runes or symbols” as an option, I instinctively imagined futuristic, sci-fi-like symbols with straight lines and clear angles, rather than the more fluid cursive symbols with curves more typically seen in older languages. I think this was probably because the programmable coloured LEDs of the Model 01 will make it look quite futuristic to me, at least. So for my tastes, mixing futuristic with ancient might look a little strange, and consequently I think I’d prefer (say) Aurebesh to something more Elvish or alchemical.
Thinking along those lines, here are some unicode glyphs I found along the lines of what I imagined, which happen to be both ancient and rather futuristic looking:
But maybe I’m wrong and a mix of futuristic shimmering colored keycaps with ancient-looking symbols on them would look totally awesome 
The points about copyright and neutrality (from political, geographical, and fictional points of view) are of course valid and worth thinking about. Rather than attempting the impossible task of trying to pick one alphabet which pleases everyone, another approach aiming for neutrality might be to pick one symbol from a wide range of different alphabets which have a wide span across space-time (i.e. from ancient to futuristic, and from all corners of the globe and maybe even fictional universes too). This might be a nice gesture towards unity in what seems to be an increasingly divided world.
Of course the challenge would be to pick symbols which somehow look nice when put together. Since both the hardware and software of this keyboard have been designed in a beautifully open manner, I guess it would be possible for this small community to collaborate on picking a set of symbols together.
I agree with @moltendorf:
I also would like to have runes on all the keys (including modifier keys).
I vote for the butterfly key to stay in the “runic” layout (if you’re counting votes).
My intended use for the runic keycaps is:
replacements for QWERTY keys, punctuation or modifiers that do not fit my needs for some reason, or are broken.
Therefore I would like maximum dissimilarity with latin letters, and especially with the corresponding key label in QWERTY layout.
Having looked at your suggestions, I find myself agreeing. That’s a first, as I was very sure I’d side with Tengwar, but dear deity, Mende Kikakui looks simple, yet elegant. A kind of minimalist beauty. It also has plenty of symbols to choose from, a nice variety of them too, to make each keycap distinct.
Terrific find.
I would not mix symbols from different languages/sets… that sounds too complicated, and hard to agree on, and even harder to find matching runes that look good together.
Glad you like it, @to1ne and @algernon 
The Wikipedia article for Mende Kikakui says it’s “still used today, but perhaps by less than 500 people”.
Started playing a bit with Mende, and U+1E80A looks like the perfect fit for an ESC key, and U+1E86D seems like a nice Any key. OTOH, ¯\_(ツ)_/¯ would look neat as an Any key too. But that’s non runic, just silly. 
My thought pattern on this had been to do a mix of different symbols from different alphabet sets, looking for the symbols that look the most interesting.
I agree with everyone else that the butterfly needs to be kept in. I had been thinking it could be a palm key. My silly side thought the other palm key could be a palm tree symbol.
I had been looking through these, and now that the forum is up, I will put together a image of what I was picturing for feedback.
I like that idea. A lot.
A work in progress image, with Mende symbols, and Butterfly on the palm keys:
Haven’t really touched the right side yet, and I’m not entirely happy with the left, either, but its progressing.
Here is my first attempt. Feedback please! I grabbed symbols from all different fictional languages, including the alchemy symbols. The symbols aren’t aligned with the keycap direction, so some look a little skewed.
@algernon I personally would like the symbols larger, since there isn’t any need to have the rest of the keycap available. I like the style you have there.
One of the reasons I didn’t make them bigger is because the LEDs are in the lower left corner, and I figured the symbol looks best when fully illuminated. But I do like the large symbols you have, too.
