Answer:
You throw me out when you want to use me and you take me in when you don't want to use me. Who am I?
A leathery snake, with a stinging bite. I'll stay coiled up, unless I must fight.
The more you take, the more you leave behind.
Twigs and spheres and poles and plates. Join and bind to reason make.
What is lengthened by being cut at both ends?
You use it between your head and your toes, the more it works the thinner it grows.