This is a fun and easy idea to create a personal festive accent for your décor. Tailor it by adding items that delight you into the scene.
Open terrarium and position birds inside. When you are happy with their placement, remove each one and attach a small amount of putty to the bottom. Return birds to their positions and press firmly in place.
Position a few trees of varying sizes around the birds. When satisfied with the composition, apply a small amount of putty to the bottom of each one and press firmly in place.
If desired, scatter a small amount of artificial snow around trees and birds for a wintery effect.