Reply to Aggressive playing toddler?

I would suggest either playing with him, and modeling how to build with the toys or whatever you are doing, or redirect him to an activity that requires higher energy like bike riding, running, soccer, climbing, dancing, swimming, or give him play-doe to smash (not to throw) and a large mat on the floor. If he is throwing, give him a ball, and take him outside to play throw... better yet, give him 10 balls. When he has exhausted his destructive energy bring him back inside and do the activity with him again, this time modeling how to do it properly. Apart of being a toddler is learning social cues and social rules, you can show an angry face, without getting angry, or a disappointed face, without really caring, and then tell him because he is smashing he is getting play-doe, or since he wants to throw, you are now going outside to play ball. This will upset him (consequence), but also teach him there is an appropriate outlet for every action.