What to make/build/create/maybe even bake with my DS age 11

[930onaTuesdayNight]

My DH has taken our other two for a drive and hike so we have several hours just the two of us. We just had a long walk and finished HW and I’d like to do a “project” together. We have a million kits and tonnes of LEGO but I think he’d prefer something we can actually make IYSWIM. He likes crafts but more the making/building rather than decorating. We baked yesterday and built a popsicle stick house last weekend. He likes science experiments but we only have normal household ingredients, although we do have an enormous supply of crafty things like paper, paint, cardboard, yarn, fabric, a hot glue gun, etc. Messy is fine. Ideally it would be something we can complete in one day.

I’ve been combing Pinterest but nothing is jumping out at me. I’d be very grateful for any suggestions!

[Penville]

If you’re ok with mess a baking soda volcano’s always fun (make with paper mache, paint/decorate and then destroy)

[viques]

If he likes science and baking then start teaching him the science of baking. Soda bread for example, or scones where you add lemon to the milk to sour it, anything with yeast , Chelsea bun variations are great fun., I do a good one with Nutella.......

What about designing and making an advent calendar, fill it with jokes , the cheesier the better, or interesting facts.

[930onaTuesdayNight]

These are fantastic ideas thank you! Love the advent calendar! And did I not think of papier-mâché?

[MayYouLiveInInterestingTimes]

You can make a rocket with baking soda fuel too. I just had a google for it and found this website, I'll have to have alook through it myself.
www.science-sparks.com/baking-soda-rocket/