My original thought was a rubber case, but then I realized that the clamshell design would make that impractical. Therefore, I suggest that a shock-absorbent plastic shell be added as an add-on, such as this one for the GBA SP:
I suggest that it be transparent so the FunKey can still be seen through it, though perhaps after the end of the Kickstarter other colors and designs could be sold. I also suggest that a leather case that fits the FunKey and this shell also be sold, such as the following for the GBA SP (though perhaps more in the style of the subsequent Switch case):
I was thinking something similar to the Plastic shell, but more in the style of a GB cartridge cases. Easy, quick to make injection molding, small hole in it for the keychain loop.
Yes, it has to be this one!
While that design would definitely cost less, the problem is that it only protects the system during transport, not during gameplay, so there isn't additional protection from accidental scratching or drops while playing games.
Please consider something that "seals" as a priority. Fabric and leather are nice options depending on someone's more formal activities vs EDC. Given folks will carry their Funkey S on their keychain, in a purse/backpack, etc. - it will be encountering much dust, lint and possible moisture/condensation. Set your keys on table, then someone spills their tea. Eeek. Hit the beach - surf, sun & sand. Eeek. Accident's happen. I want to protect my new EDC so it has a long & happy life.