To form a cluster, write all ideas on post-it notes first, then place similar ideas in groups on a large sheet of paper. Then name each group and take a photo of your clustered ideas to record how they were grouped. For voting, give participants a certain number and distinctive type of stickers (eg 5 gold stars) and ask them to vote on their favorite ideas. Participants could use all their votes on one idea or spread them across a number of different ideas. In to the next design stage progress the idea(s) with the most votes.