DS is turning 5 in October and I'm looking for some good suggestions for presents. He really enjoys science & engineering type activities.

This entire year he's been super into the Magic School Bus books. He's very interested in the solar system/space, gravity, electricity/energy. And he likes to take things apart and put them back together.

He loves our 2 kits of Snap Circuits (the general jr kit, and the radio kit). We have a couple cars you can take apart and put back together, but they've been around while and are too simple now. He would enjoy them more if they had motors and electricity, for example, but they are just plastic pieces. We have some legos (just plain blocks, hand-me-downs from when my little brother was young), Magnatiles, and wood blocks that all get played with sometimes.

I think he would love some toys he could take apart, put back together, and that would DO something. Sorta like Snap Circuits, except we already have those and need Something Else.

I would also love suggestions for actual devices that it would be safe for him to take apart, that could be gotten cheap at a thrift store or something. Last week we had to take our Roomba all apart after it sucked up cat barf (ewww) and he was in heaven.