From Marguerette's Supply List (I'll post it as soon as I can scan it): "A must have for the workshop is a Foam Core Board or something to use as a design wall, 20" by 30"or 30" by 40". Anything larger will not work."
And here's the FYI - 99 Cents Only store have the 20 x 30 boards for 99 cents in their stationary aisle. At least the one on Arlington Ave/91 Freeway does - I bought one this morning.
Need info for this May 24th workshop? Go here and here.
Sign ups at the April meeting.