Here is the full list of all 49 Create achievements worth 1,000 gamerscore. It takes around 30-35 hours to unlock all of the achievements on Xbox 360.
Solved 20 player generated Challenges
Solved 10 player generated Challenges
Remixed and saved a downloaded Creation
Downloaded another user's Creation
Uploaded a remixed Creation
Submitted an entry to a Community Challenge
Saved a Creation or a Challenge from Free Create
Solved Challenge 10 in Transportopia entirely with Horseshoe Magnets
Solved a Contraption-o-Matic Challenge with a contraption built of 40 or more parts
Used every type of rocket within challenges
Eaten 50 slices of toast
Used every brush in Paint mode
Placed all types of animals throughout the game
Placed the Create team's favorite animal!
Collected all 610 Sparks
Marked the content of 10 different online users as a favorite
Completed a car based challenge after all its wheels had been burst
Collected 501 Sparks
Marked an EA Pick as one of your favorites
Marked another user's content as one of your favorites
Downloaded an EA Pick
Unlocked Future World II
Rated the Creation of another online user
Attached 50 objects which have string to Challenge objects
Unlocked Outer Space II
Unlocked Family Home II
Unlocked Theme Park II
Collected 284 Sparks
Unlocked Darkworld
Unlocked Pirate
100 balloons burst
Unlocked Urban Sports
Unlocked Future World
Unlocked Ancient History
50 explosions set off
Unlocked The Great Outdoors
Collected 100 Sparks
Unlocked Outer Space
Solved a player generated Challenge
Reached a x20 multiplier in a Scoretacular Challenge
Driven 2,000 meters in vehicles within Challenges
Unlocked Family Home
Finished five Create Chains on a level
Unlocked Transportopia
Uploaded a Creation
Uploaded a Solution
Unlocked Theme Park
Solved your first Challenge
Earned your first Spark