I am looking for robot constructor general plastic parts

Projects Discussion and Showcase Robotics
#1

I do not know how call it, but I mean something like these pics:

Can I find something like this plastic parts in general or I must design them in solidworks and ordering for mold production by myself?

My goal is to build some educational robot kits for kids by this parts.

#2

Like this?

#3

Yes, but something has more parts. Also I couldn't understand what material the parts you put are made of?

#4