Every day after lunch my daughter (2.5 yo) spends an hour in her room playing and reading - her 'quiet time' and my 'sanity time'! Yesterday for quiet time we built a cubby. It was constructed from retro sheets (ie, my mum's old ones!) and she loved it! Evie took in her pile of books, bedroom lamp and favourite toys and lasted the full hour quite happily. We've done the same today (she's in their now) with the addition of a dolls crib and tea set - perfect!
I remember this feeling as a child, having your own little space - heaven!