I use two kinds of modeling tools in my form studies:
A commercial magnetic spoke-and-hub tool called Dyna-Magz. This tool works great for quick studies and smaller forms*. However, for large complex studies it is too heavy to stay intact as a form’s node count increases. The small strut size also makes it difficult to work the model with your hands as the complexity grows. So, there is a practical limit to form complexity here.
A tool I developed and placed into the public domain called: Compensating Skeletal Geometric Modeling System:
This is a very light-weight tool with a strong attachment mechanism so it can support large build-outs. The struts can compensate length to a small degree to get past certain hurdles. It is intuitive, easy and fast in build-out, and importantly, easy and fast in model take-down. The strut length I use is about 7″ so it is easy to get your hands inside and out of the model to work with. In sum, it makes explorations easy and fun.
*In the models shown in the essays that use the Dyna-Magz, the strut colors are random unless otherwise evident.