Welcome to a loose guide on Crystali design. The main things to keep in mind are that they are digitrade anthro critters. They don't typically have tails, instead their spines end in a cluster of crystals. The tail crystals always emit a soft vapor of trailing magic that mimics a tail. They have 2 main clusters of crystals on their heads, sometimes mimicking horns. Their claws are of the same material as their crystals and should always match. Their flesh, eyes and any other area that isn't naturally covered in fur will also share the bright color of their elemental crystals.
For information on rarer traits, please visit the traits page! Anything unusual will be explained there. The information on this page is just for “base” crystali.
As mentioned, all Crystali have crystal “horns” and a crystal cluster as a “tail”. These clusters must be present in all common crystali designs. They can be different shapes and still be considered common (Within reason).
Crystali have a trail of magic as a tail. The intensity/size of the tail can vary. sometimes the mist can feel warm or static-y to the touch. Sometimes it can be intense enough to slowly change the temperature of a room. The mist doesn't have to perfectly match the color of the crystals, but it should be a similar tone and not look too out of place to count as common. color gradients are quite common as long as the colors are next to each other in the color wheel. The tail can also sparkle or have subtle nods to a strong element. For example, embers if the element is fire, or some static for electricity.
The cast channels are the markings that usually look unatural/runic/tattoed that glow with a Crystali's element. The markings are on the skin and the hairs that grow there are like fiberglass so the glow shines through. It's bright enough that in normal daylight they're very visible and saturated, and in darkness they emit a soft glow. If done properly (by someone trained to do it that my brain hasn't birthed yet), new markings can be added via something similar to scarification to add further symbols to amplify magic use.
The cast channels are supposed to be 1 single color per element, but like the mist a slight gradient can be used. The gradient should be 'per marking' and not just a single gradient from head to toe on all the markings. Common Crystali magic channels shouldn't emit any sort of magical effect (only a glow in darkness).
The fur can be any and all colors on a Common Crystali. They can be as bright or desaturated as one would like, and the fur can have any patterns as long as they are somewhat natural looking, but there's not really any set rules. Just make sure they 'vibe with their element'. Unlike the rules with their crystals and stuff, there's not really any limit to the colors and patterns in their fur.
Crystali hair is a strange thing. Sometimes it grows like hair that can be styled, and other times it's more chaotic and will act as more of a mane. The hair on their necks can play into their “hairstyle” and it's common for polar Crystali to look very fuzzy around their heads.
The ear shape can vary a lot and have fur of various lengths. Long ears can be docked and it's really common for poor and working class Crystali to have shortened ears to avoid them getting in their way.