My daughter get the Kiwi Crate (gifted subscription from Grandpa), for about a year now, and it's an absolute highlight of our month. We make a day of it each time one arrives and put together a little video of completing it to send back to Grandpa. It has become very special to all of us.

They've created something really amazing with this. Other crates/boxes/etc exist, but they consistently nail the balance of challenge vs fun and overall quality. My 5 year old can follow the instructions herself with only minor prompting from me, and you always get some form of lasting & inspiring object afterwards rather than just stuff that ends up in the bin like many other similar programs. Her room and our house are littered with things she's built herself and that still get use many months later, and they've taught her heaps about how things work.