I've got this idea of improving builders from Bajantara today. I haven't had the opportunity to try it yet, but you're welcome to it anyway. I hope you don't mind, Bajantara, if you read this. I dedicated it to you anyway. Highlight the empty spot down here by clicking the left mouse button and drag the mouse down over the spot and the text will be seen. I did this so that those who don't want spoilers will be warned and have the opportunity to avoid it.

Apparantly some stews are good for builders and those kids who will be builders in the future as well (they gain skills). Here are the instructions from Bajantara:
"The 2 "exercising" stews:
orange + red + red
or
red + red + red

When the villager finishes exercising and is successful, their building skill increases. A little odd.. we figure they must be "building" muscles, abs or stamina.. lol"