activity ideas for 15 month old

I have a 15 mo son and we also have a 4 week old baby. The baby obviously takes up a lot of my time at this stage and my toddler has been spending alot of time during the day with his gran and then at night my husband spends lots of time with him, doing his tea and bed time routine etc while im feeding the baby. My son loves going to his grans and spending time with his dad but i feel like i hardly get to spend any time with him and like our bond is disappearing :-(
When he gets upset he prefers to go to his dad over me, i try not to let it get to me but cant help it sometimes.
Anyway, im really womdering if anyone has any fun ideas of activities i can do with him at home to create some special mummy and son time. I dont have a lot of time to set things up so im looking for fun tnings that are easy to do. He is very busy and doesnt like to sit still for books etc and he still puts everything in his mouth so things like playcough are not an option.
Thanks for any suggestions!!!

You could try baking with him? I just buy those boxes from the supermarket where you only have to add an egg and water or some such thing. My DD loves it. She sticks her finger in when she thinks i'm not watching and loves putting on her apron and standing on a chair to "help". I tend to buy ones that need decorating like the cupcakes or the whoopie pies.

I also went to the $2 and bought a set of dinosaurs. When the baby is asleep we sometimes set up dinosaur gardens on the tile floor with a few stumps of wood from the wood pile, a few branches or leafy fronds, rocks and a little bowl of water for a pond. We spend so much time setting it up together that often that's the extent of our play rather than having to come up with a storyline for the dinosaurs once it's done.