Rainbow CollectionG 30

You can get this within 5 minutes of starting the tutorial level. Upon leaving the beginning part of it make you way to the castle just left of the fountain. On the bridge to it you will see a sand village off across a pond. Go there, and standing on the furthest side from your starting point, look to your right you should see a vague outline of a ship. Go there. There will be a massive house next to it (X: -169, Y: 83, Z: 322). And just as you walk in the front door, first door on your right, should say imagination room in it will be all the colours of wool some diamond blocks and a lot of other things.

Credit goes to http://www.trueachievements.com/viewcomment.aspx?commentid=830861#vch