The Custom Colors cost 2,500 coins and require you to have 5 total colors bought from the store
The Custom Tricolor costs 4,000 coins and require you to have 5 total colors bought and 4 vertical colors bought.
This allows you to change your curve color into anything you can think of.
A curve can have up to 6 (or 18 with Custom Tricolor) different colors at a time and you can choose any of the avaliable colors you have unlocked.
Use UP/DOWN to cycle through the available colors for the selected color slot.
Use LEFT/RIGHT to cycle through the color slots.
The hud's text color depends on the color in the first slot.