Usually, to produce 3D object models on one will have to use a computer. Even for people who are good with computers, it usually takes some time and a lot of tinkering to be able to model proficiently. A lot of people will rather avoid cases where they use 3D models for demonstration than learn how to use these programs. We try to solve this problem by using a set of mouldable objects that can be made into a wide range of shapes without losing their malleability while being strong enough to stay in the shape that they have been molded into once they have been shaped. These types of objects can be used to form simple 3D models with just your hands and no skills or prior knowledge is required to use them. Even a blind person can form 3D models using such a tool. These collapsible 3D models can help blind people to visualize solid objects better. This will also go a long way to facilitate the education of blind people and improve their employability.
The objects will make different sizes will have ends that can be attached to other objects so that they can be made into joints.
The real-life example that I have come across that has the qualities closest to what I have in mind is a wire. Wires can easily be bent into the kind of shapes you want but they can not be flattened easily. After being flattened it is difficult to mold them back to shape.
A possible implementation will be a low-density dough-like material that is placed in an elastic case. Wires can be used as the object's "skeletal" system so that it is easier to form edges with their sides. They can have buttons that have many prongs and hooks so that the joints can be formed between objects. The buttons should be detachable so that joints can be made to any area of the surface.
If possible the dough-like material should be something that can be hardened or softened by wetting it or drying it respectively.
Another approach towards implementing the idea is to use a lot of short wires that are joined by small threads so that they can move relative to each other. These wires will be enclosed in a flexible case too. The object will have strings that can be pulled to reset the assembly of wires to their default arrangement whenever they are entangled.
Advancements in nanotechnology will make it possible to create much better versions of such a tool. This can be modified into a DIY object construction commodity in the future.