What are the names of the legs / fasteners that can increase when untwisted?

Question

Do it yourself

I want to make a shelf so that it stays on the principle of corner shelves in the bathroom when you unwind them and rest against the bathroom and the ceiling. What is this mount called? I want to fix the shelf like this between the walls. just to withstand 2 kilograms and that's it.

Answer 1

pedestal adjustable
pedestal with swivel joint

Answer 2

Google for "joker system"

Answer 3

"Adjustable screw supports" they are called.

Answer 4

And another option on the site https://lb-total.ru you can pick up all the necessary details. I like very comfortable.