Here is the official explanation of what the Activity is, which can be found on the same page where builders should share their submissions:
It’s red, orange, yellow, green, blue, indigo and violet… Any guesses? That’s right, we want to see your best rainbows!
This is part of a series on LEGO Ideas that gives little tasks for builders to get involved with – there are no prizes, they are just a way to get involved with building something quick for fun. Each challenge is intended to be something quick and fun, unlike the more in-depth building required for a competition or product idea.
The deadline for this Activity is May 26 at 10.00am CEST.