For this project, this is something that can be dismantled at the end of the holiday season and repurposed next year, so everything is non-permanent. You can always add a little glue to hold everything together if you'd like.Start by creating a "trough" to hold your snow. Do this by cutting a piece of clear packing take as wide as the bottom of the box and then trim it down using a craft knife to fit the shape of the box.
Then lay out your winter shadow box using spools or other objects to lift your items. Didn't like how low the camper sat on just the spools, so the battery pack for the fairy lights was put below it and that worked perfectly.
To secure the fairy lights to the back of the winter shadow box, use a few small pieces of tape. The plan is to leave the lights on throughout the season, but you can also flip the little switch by reaching through the snow if you want to turn them off for some reason.Finally, scoop some fake snow into the "trough" you created to cover the battery pack and spools and you're done!