A "leftover pellets" case would be great if it's very obviously such a mix- so it doesn't look like an accident of poor quality standards. The case is perfectly practical polycarbonate, coloured with mixed-in pigment rather than surface-painted, and it would be nice for it to show that fact proudly.
Of all the case colours I've seen photos of so far, the pastel violet one is by far and away my favourite- assuming that actual production ones will use the same grey nubs and buttons and stuff for all case colour options. I'd be similarly thrilled with lotsa tints, shades or tones of orange, violet, or green, though. I like those hues.
It's prolly unlikely that either "changeover" or pastel violet will make the production offerings, but whatevs. At this point it looks like that soft, easy-on-the-eyes red & grey scheme is gonna be an option, and I'd be quite satisfied with that.
That's prolly for the best, as the red & grey would look more appealing to random peops I run into than the "Willy Wonka" look I'd otherwise prefer. Some of the appeal of the Pyra is that every time this human uses a PC in public could be a chance to encourage awareness of and interest in fair & open design philosophy, (particularly FOSS software) as well as the fact that modern computing hardware makes it quite technically feasible for one's smartphone to also be a fully-functional palmtop PC & pocket game console.