I just love seasonal and holiday shadowboxes and have made many over the years. Some were decorations, some were given as gifts and some have been for sale.
The shadowboxes were mostly made out of 1/2"x 1" pine for the frames and 1/2" pine boards for the centers. The frames were painted one color and the center boards were painted another. And, rub-on stencils were added to the center boards to complete the pictures.
There was only one exception to the total wood picture and that was for the snowman picture shown in the third row of the collage above third picture from the left. That shadowbox was created using pine wood for the frames and an 8"x 10" canvas panel for the center. Like the other shadowbox pictures I painted the canvas panel a different color than the frames and then applied the rub-on stencils that I had purchased at various arts & crafts stores to create the picture. Brush on varnish was added to seal everything.