I don't know a child under 16 who doesn't love a fort!
We recently purchased glow sticks at Michael's (15 for a dollar!) and it seems like the perfect toy to introduce with a fort! That or flashlights, nightlights, etc. ESPECIALLY if you have a nice dark basement to build a fort in!
Everything you need for tomorrow's challenge you already have! Ask your kids for ideas for what to use for the walls (we always rearrange our couches and kitchen chairs to assist us....)
What can you use for a roof? (obviously blankets and sheets work the best, but let your children come up with some ideas of their own!) D suggested we fill ours with pillows inside so he could nap in there. I thought this was a pretty fun idea, so tomorrow for his FOURTH birthday he is allowed to have his "rest time" in his fort.
Put a stack of books in the corner, some dolls, maybe a tea set so they can have a party.
My kids will go back to the fort all day long. Quiet play, loud play, games, naps, meals... it's a day long party.