what type of projects?
add more info!
The theme would change the possibilities. For example, if you are doing a travel theme you could use some scrapbook embellishments. If you are doing an ecology project you could use some recycled items. You can use a t-shirt to cover the project book then sew on some embellishments. You can sew on jewels, charms, wood beads. You can wrap it with ribbon/jute/hemp or leather. Hope you find something fun!