What would you recommend for shadow boxes?

i want to make shadow boxes for my parents to hang in their bedroom. i want to make one for each of my brothers. should i have them find things that they like to put in. if you have any other ideas please let me know or if you think my idea is good. thanks|||Put things they enjoy...for instance if one of your brothers likes cars, put things about cars in there.|||If it was me, I would find items from grandparents that are very memorial. Good Luck