'Chromas' should be Customizable and only unlocked via Champion Mastery.

It should be as simple as:

1. Select Champion via the Champions tab.
2. Have a little icon that you hover over that says 'Model Customization Available', if it's not available it would be greyed out.
3. Click on the icon.
4. New window comes up with a model of that character's Default Skin.
5. Tabs down the side that select the region you want to recolour. E.g. Zed: Left Side Head, Right Side Head, Left Side Face, Right Side Face, Left Side Torso, Right Side Torso, Left Side Legs, Right Side Legs, Misc 1,2,3... (in Zed's case his Red Scarf/Hood and any trim/details in his armor, weapons etc).
6. After selecting the region, select the colour from a list.
7. Confirm

These SHOULD NOT be Chromas. They SHOULD NOT available for RP. They SHOULD only be available on champions' base skins. They SHOULD only be unlocked via champion mastery. They SHOULD ALSO have an IP cost attached to them (i.e. They become Available upon reaching a certain level of champion mastery AND THEN you can Unlock them with, say, 1500 IP).