Twilight Sparkle and Princess Luna have been working on this for quite some time now, and it's finally time to put the cube to good use!

This is an intricate arcane contraption, specifically made for Princess Celestia. Its function is to confine her brilliant body and magic, as well as retain her in perfect condition perpetually! The actual physical device was designed and assembled by Luna, who's in fact proficient at fine arcane engineering. Twilight infused it with her magic along with the all the right potions and fluids required for its specific operation, fine-tuning everything for their target.

The cube keeps everything inside it in an optimal condition and balance. As you can see however, some parts of the Princess are sticking out, providing easy access and a beautiful view~ This is on purpose of course. Twilight has secured an enchanted amulet between Celestia's feets, which keeps concentrated beams of magic on her soles at all times, idly moving them around over the day. While they don't provide much sensation or stimulation, this magic increases her pedal sensitivity and it even adds up over time! Indefinitely! Of course, the bar from which the amulet hangs from prevents the Princess from rubbing her feet together to get a feeling of exactly how hypersensitive she has become. That will be a tingling surprise for when Twilight decides to visit and play with her coveted feet~

Luring her inside it was much easier than you'd think. Twilight knows everything about the Princess' kinky curiosities, so it was just a matter of waiting for the right time really. Working up her mood and suggesting some "special bondage play" during their vacation was all that was needed~ The drinks certainly helped too.