Here are some of the items you may have or be able to buy cheaply:

FeathersBeadsPipe cleanersRibbonGoogly eyesCraft sticksButtonsColored paperYarn

Supplement these items with odds-and-ends and recyclables:

BoxesPlastic tubsPlastic bottlesLidsMagazinesGreeting cards

You’ll need scissors and a couple of different types of glue. A low-temp glue gun is a good choice for older children.  Put everything in a box. When the grandchildren come over, cover a table with a protective cloth and let their imaginations run riot!  Accessories such as belts, scarves, hats, and ties are great fun for dress-up. Add costume jewelry, tiaras, Mardi Gras beads, feather boas, parasols and leis for more flare. Tuck a ring of cast-off keys into a purse or a sheaf of papers into an old briefcase to enhance the play-acting. Besides finding cast-offs in your own closet, you can shop thrift stores and garage sales. Find fanciful accessories at party shops, costume stores, and dollar stores. After-Halloween sales may allow you to add real costumes at reasonable prices. Always supervise young children during dress-up. For maximum safety, keep them in their own footwear.  Add mementos such as a pretty stone from a childhood rock collection, or a small vintage toy. Have a family story for each item and be prepared to tell the stories. Allow your grandchildren to add an item or two that they treasure, or encourage them to start their own memory boxes. The grandchildren can create their own backdrop, or for greater realism, you can find an appropriate scene online and print it out. When I was a child, we used to make peephole dioramas. We created scenes inside a shoebox, then cut a peephole at the end of the box. A square cut out of the top of the box and covered with colored cellophane allowed just enough light to create a mysterious scene. If you have a green thumb, consider creating a fairy or elf garden instead. Find an appropriate container, add small plants and arrange tiny accessories. You can make lots of fairy garden accessories from natural materials. Remember that getting letters is just half the fun. Learn how to make your letters to your grandchildren extra special.