If you are curious to what trait something might be, you are free to note the group and ask! Most unlisted traits will be either Very Rare or only available for Lucid Dreams or Nightmares, as they are odd features to have on your average Doot Doot.
Eyes
Heterochromia of any kind is rare~
Any colored sclera other than white is rare.
Anything unlisted is very rare. Glowing eyes are only found in Lucid Dream / Nightmares.
Horns
Simple and smaller horns are common, while more complicated horns become rarer and rarer. Textures of the horns are seen below.
Ears
Unlisted ear shapes are considered very rare, while multiple ears are for Lucid Dreams and Nightmares only. All ears listed can be a little more or less furry as long as it's clear which ears they are.
Scars and piercings are fine for any ear type!
Tails
Unlisted tails would be for Lucid Dreams or Nightmares. You can add more or less fur onto tail types as long as it is clear which tail class it belongs to!
Curly fur is welcome to any and all tail types!
Wings
It is common for Doots to have no wings, as they are young or adults they do not sprout them into their later, much later, years when they earn them. It is uncommon for a Doot to reach that stage. Wings can only be feathered (any other wing type is considered Nightmare or Lucid Dream).
While the uncommon Doot can have any design for their feathery wings, Lucid Dreamers can have actual essence for their wings (see "Essence" under Mythology). These wings are often reflections of the Doot's essence and act like essence in the sense it seems like its constantly moving space.