Thole pins: As wooden pieces get smaller, you reach the point where you begin to “fight the grain.” In other words the grain begins to weaken what you are carving. The classic modeling woods; boxwood, pear, apple, holly, have very close, tight grains as well as strength to allow carving and turning into very small items. No so, basswood. It is too weak. So, either switch to a harder, stronger, close grained wood, or use a different material For example, painted brass wire.
If you use wood avoid cross grained stock. Choose a piece with straight grain and split rather than saw it.
There is nothing wrong with using different materials to model parts at the required scale.
Roger