Update: Less than 24 hours after I hatched the plan and put them together, all 100 bracelets have sold. And we made £30 more than we should have (raised £138.50). I think Mr. O's tutor group is now going to give the same thing a try.

Next day: Made another hundred, purple and green wavy lines this time, and sold 60 already. Mr. O. needed help, so I printed him some polka-dotted paper, and now he has his started, and plans to be ready to sell on Monday, as he is a typical man who needs a woman to get him started (kidding, TJ, if you're reading this!).

Final update: All 200 bracelets sold, made £240 for the charity. I'll repeat this one again -- it really worked well.