make a pirate ship from an empty cardboard box - plastic sheet on teh floor, they can spend ages painting it and then sitting in it and filling it with toys
Baking - not necessarily for real, just playing with real kitchen equipment. Balance scales are great for just measuring etc....
and if you are up to it, just really simple cupcake baking and eating - I have done that with mine since really very young. also decorating biscuits with icing pens etc.
playdough - I find soft stuff from elc, which I buy by the bucket load when it is on sale, is great and doesn't go dry really quickly. mine spend hours doing it!
sticking and glueing - I cut up lots of bits of old wrapping paper, cards etc, and then we just happily sit and stick and glue!!
If you have any space outside, I have a little water/sandpit table, that I only put water in as sand goes everywhere. they spend hours playing with jugs and empty yoghurt pots etc just pouring, and watering plants, and throwing water around. We literally have a postage stamp sized patio as a garden, and this works great.
As twofalls suggested - get a big roll of paper, draw round them and then again spend hours sticking bits of paper etc on/colouring in, then have a life size toddler stuck on the wall!
inner rolls of cardboard from wrap rolls make great swords for play fighting
Stickers - lots of them! don't buy those really expensive little packs of stickers. If you google Melissa & Doug stickers on Amazon, they have massive books of stickers, literally thousands, for about £3.99....