Costom capes or Elytra textures

I was thinking that you can upload your skins to Minecraft to wear I thought that it would be cool to add a feature where in the marketplace in the cape section you could upload a png for capes and possibly could turn into elytra's. Another Idea is that in game there could be a way to add a banner design to a elytra like the sheild with a banner. 

Also I do suggest modderation on this because there could be some 40 year old with realy inapropiate stuff than a 5 year old sees it so I would suggest guildlines or deletion of cape or ban.