Yep, as others note -- Time for you to sweep the house, yard, and garage for all tools, ladders, even individual nails, and I'd include the scissors etc. too. Put away, lock up, ensure he can't get at them. This also will be good because eventually you'd have to babyproof for the new baby anyway, right?
But then: Do lots of projects with him, find lots of hands-on things to "assign" to him, give him household responsibilities! He is not being defiant or bad, so much as he is being extremely curious and hands-on. Please feed that positively instead of quashing his energy and his tremendous curiosity. He's going to be a tough kid to keep busy and involved but you can do it, and you may end up with a wonderfully handy teenager one day.
Get small kits from the craft store so he can build stuff (no airplane glue, strong adhesives or real nails). Work alongside him as much as you can and for the rest, find things he can safely build on his own. Since building alone may be tough, would he like to paint things like a birdhouse, a small wooden planter, a wooden footstool, a little wooden trunk? I see them all, unpainted, at the craft store. Let him have a space where you will not care if he spills paint or gets it on it, and let him go at it. Get him a toy workbench with as many "tools" as possible.
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Is he into building toys? How about large Legos etc.? (Have to keep those away from baby for a very long time yet, though.)
If he's interested in the bird's nest--has he been to the zoo or a nature museum any time lately?
Have you tried having him help cook, which is a terrific way for any child to be helpful and handy? Give him things to stir and whip and let him pour things into pans etc. Again, be sure this all happens in clothes and in places where you don't have to say "Oh, don't get messy!" because that will frustrate you and dampen his enthusiasm.
Water play, sand play, arts and crafts (yes, boys can be into them, and not just into tools). You can find plenty of arts and crafts you can leave him and his twin to do nearby with less supervision.
Punishing him clearly isn't having your desired effect of "making him understand he isnt' old enough to do everything on his own yet." Try to think like he does, not like an adult. In his mind, he IS capable; help him find and do things that make him feel even more capable but are age-appropriate. Make him "the boss of the dishes" in charge of clearing the table, while his brother is "the boss of the floor" and cleans that, or whatever. Make it a game, or see who can finish first.
Telling him "I'm just trying to keep you safe" does not really mean a lot to a child this age. They don't understand what "safe" really means because they have never experienced being hurt by the things they are doing, and are not really mature enough in their thinking to look at a hammer and say, "Yes, I think that would hurt if I hit myself with it because it's heavy and hard." He's not wilfully ignoring safety; he just does not have the understanding yet to fully grasp what safety means, so your words to him don't have the impact you want them to have.
You have a great opportunity to channel his energy and curiosity into a lot of learning, but he will require a lot of watching and guidance. You don't mention if there's dad in the picture but if there is -- Dad could spend hunks of the weekend doing projects with the boy.