They are an excellent idea, I took the idea/s I found online but then cheaped out and built it using primarily 2 x 4's it's strong and sturdy and with a good set of locking castor's works like a dream.
I got the layout and info from Instructables
I tried convincing a buddy of mine to build us one but he is going to Mexico instead 😞
I saw an interesting woodshop project. It could help us have more woodshop tools.
https://www.instructables.com/Multi-Tool-Flip-Top-Table/
I don't have time to build this. I'm just passing this idea along.