Chopsticks
Lex spent the next 2 days getting used to the changes in his body. Getting used to his new strength was the easy part, as his brain did most of the work for him. To further refine his control, he used chopsticks to move rice from one bowl to another, one grain at a time. The chopsticks themselves were quite flimsy, and every time he accidentally broke them, he started from the beginning.
This method seemed pretty stupid when considering all the resources available to him, but sometimes it was just about putting in the work. He quickly gained precise control over his strength, not only in both his hands, but his feet as well - though he hadn't used chopsticks to train them.