hmmmm. No idea since I don't know know much about any manufacturers. I've just shopped at Joann's, Creative Memories, Stampin' Up
My ideas:
color challenge. Each challenge has a specific color that you must mostly use
product challenge: each challenge has to use only embellishment or tool specified (and somehow provide for substitutions for those that do not have said embellishment or tool)
use up a paper pad
only scraps
use pages from an old magazine as an inspiration
rooms of the house
maybe a month when someone else provides all the challenges. I'd be willing to "sponsor' a month of challenges
Bring out the artist in you.... use brush strokes
Color wheel challenge
your favorite color theme
Colored circles
enhance your creation with colored items
Box of crayons inspiration
How does your canvas start?
