Shadowbox idea for The-Paper-Pony's contest (the-paper-pony.deviantart.com/…). If I was digital artist I may have tried to draw this but I wouldn't be able to with my limited supplies D: Plus my masters is mean right now. Anyway on to the idea!
CRYSTAL PONIES! Imagine Rarity freaking out excitedly about being a crystal pony with Princess Cadence. Rarity would be on the right of the image looking over at Cadence yelling how happy she is. (References: drpancakees.deviantart.com/art… and cubonator.deviantart.com/art/C…) Cadence would be laughing at how happy Rarity is. (Ref: swiftywish.deviantart.com/art/… and bubblestormx.deviantart.com/ar…) This would all take place on the balcony of the tower or where you could see the tower in the background. (Ref: www.deviantart.com/art/Crystal… or danton-damnark.deviantart.com/…)
Now you make ask how in the world could I make a Shadowbox with crystal ponies work! Well I have a few ideas that could be used. First, a layer of white tissue paper (with glitter or place glitter under) could be used to cause the lightening and sparkle effect. Second crinkling tissue paper could create the facet effect the crystal ponies have. Or lastly you could use the paper seen in the Cadence and Shining Armor shadow box already produced
Hope this enough info!