I built this project from angle irons, a metal rod, a long nut, and a few other custom parts that I designed

First, I had a company produce the custom parts I needed by sending over the technical drawings. 

After receiving the parts I needed, I was able to connect the seat to the metal rod using bushing.

I aslo welded a second bushing to the middle plate in order to keep the rod straight and allow it to move upside down.

One of the last things to do was to weld all the parts together and sprayed them with paint.

For making a seat I used a 3 cm thick plywood. I took a wooden board with a nail and a pencil as a makeshift compass. I drew a circle and cut the seat using jigsaw.

Lastly, I screwed the seat to the metal plate.

To see technical drawings and blueprints of these and other my projects click this button: