I've found a cup holder adapter to fit a standard Nalgene, but haven't checked to see if it fits the 5th gens or not. Thingiverse thing:5960811 since I can't post links. I'm interested to see what all ends up being printed for these as well. And drag out the 3d scanner if need be to replicate some stuff.
Overall the car is well thought out, I haven't come up with a need to print anything yet. Those fortunately cup holder adapters aren't required for me as our standard Contigo bottles fit nicely, though I can see the 40oz one needing an adapter.
I’m investigating a cover for the wireless charger…maybe…If a liquid gets spilled in there is the cavity sealed? Cleaning the cavity would be hard for either dry or wet messes.
I'd like something to split the glovebox in multiple compartments like they sell partitions for other models. Could be 3D printed but I can't say I feel like designing it. There isn't much made specifically for this car so far.