What is Lemon Hearts hiding?

Lemon Hearts does not wish to be disturbed from her shop, but what exactly is she doing? is it fashion related, or something completely different?

Or is it really Lemon Hearts AT ALL??!

File:Lemon Hearts appears in door window S9E24.png

File:Rarity speaks to Lemon Hearts through window S9E24.png

File:Spool of thread falls through mail slot S9E24.png

You have 45 minutes to draw and 15 minutes to submit. Have Fun!