Balsa had been use in the past for lures but its not a really good material for a number of reasons... It floats "on top" of the water, its weak, strike from a strong toothy gamefish will make the lure a one time use object..
You need to use lead shot or plugs and dive planes if you want a balsa lure to be a popper, a diver or deep lure.
Also with balsa you have to carve channels to connect the hooks and the eyes...then fill them.
And yes I have hand carved lures from balsa....
With molded plugs you just fill a mold trim it and paint.... you can use materials that are neutral buoyant , heavier or lighter than water... epoxy, plastic, polyurethanes etc...
This is one reason I have not made my own lures in years...
Most of the time it is as expensive to make as it is to buy
Like the OP mentioned it is a great father son project, which is where I learned how to do it...
I still tie my own flies though.... can lose a dozen of those a day easily...