We have one of these. For us, the best thing has been to enroll him in piano. He's very good in piano- but it doesn't come to him as easily as other things in his life. When the songs first started getting hard, he'd slam his fingers down on the keyboard and scream "never!" then storm out of the room. I just stayed calm (barely) and escorted him back to the piano and reminded him that I only respect perfectionism in one area- effort. We had lots of talks on the piano bench over the past year or so about what we can control- effort, persistence, etc... and what we can't control as much- outcomes. And we had many opportunities to discuss that he's not going to be perfect at every song right away, but he can be "perfect" in his attitude and practice the "perfect" amount of time. He's made great strides and I've noticed it affecting other areas of his life in positive ways.
Your upcoming project may be a great place to start this discussion in a regular way. Any activity that makes these kids face their lack of perfection daily in a safe setting with support and encouragement seems to be a gift to them. I'm fairly certain tackling this at a young age is MUCH better than waiting until they are older.
