Step 1: The Base
I put two wheels on it to be able to move it. But I recommend to put another two wheels on the other side because it will get very heavy with the concrete top.
Step 2: Making the Sink
Then I started building on the frame for the concrete with sized holes holes where they will fit. The hole for the cutting board is made by two layers of wood. One in the same size as the cutting board, and one a little smaller. I wanted it to be empty underneath the cutting board to save some weight.
The reinforcing bar is made from an old dog cage. The smaller holes the stronger it will be. Make sure it doesn't touch the bottom of the frame which will be the top surface when it's complete.
Dont forget to add a bolt on either side to be able to attach it to the wodden frame.
Take your time when you add the concrete, make sure you dont get any air bubles inside.
Step 3: Adding the Final Accessories
Add as many hooks, and things as you find necessary.
It's all in the detailes.