This pack was introduced on Artsy April update and costs 30,000 Gems in the store.
Store Description: Want to paint your world? This pack includes a Rare Paintbrush, and 20 buckets of random paint colors (may include Varnish, to clean up your messes)! You can paint any block in your world different colors to personalize it.
NOTE: In a patch on April 2nd seth & hamumu made it so world locks cant be painted and you get a text saying "Thats too special to paint".
And 20 random paint buckets. These are: