3 and 5 years old here. They can get interested as long it's short and they can do meaningful work. I've teared down a second hand game boy color that had his fair share of Pepsi in it. The old one helped me clean with a toothbrush for 10 minutes, then he had to show me what parts were going where (with guidance). Then boot up and verify it works. We try to include them in everything we do and they love to help. We try to avoid the "it's adult business" and they just sit around and never be interested on whats going out around them. The 3 year old can cut mushrooms with a wood knife and the 5 stir them when cooking.

It's definitely more work, stuff will be broken but I think it's worth it.