Wiosi Mini Garbage Trash Pen Holder for Desk, Pack of 2, Blue & Green, Tiny Recycle Bin Pencil Holder | Storage for Pencils & Pens | Office Stationery to Organize the Desk | Ideal for Student Work

You could use your son's toy trucks as weights and decor. For favors, maybe desktop garbage cans/dumpsters? Like these: https://a.co/d/09L5pEjR ETA: you could even use those as the favor "bag" instead of a disposable bag. Put a piece of candy and a small toy inside.