I found a book at my local library called "Great Civil War Projects You Can Build Yourself" by Maxine Anderson. This is a great resource, with more varieties of projects than any other book I've seen. I would say that most of the projects fall into the UG/D category, as far as difficulty-level is concerned, but I've been able to adapt for LG kids fairly easily. Most of the projects use fairly easy to find materials, with a little planning, and there's a wealth of information to explain the significance of the items. I highly recommend this book to anyone trying to fit hands-on into their schedule, or leading a co-op with hands-on projects.
Robin