A couple months ago, I discovered that "welding tables", meaning
sturdy tables with thick steel tops 3/8 to 1 inch, are very hot
selling items, desired by many people and easy to sell.

Right now I have several steel plates of such thicknesses and a
quantity of 2 inch pipe.

I plan on making tables by just cutting off 30" or so pieces of said
pipe and welding them as table legs to the plates.

My questions are

1) do they need any reinforcements, such as cross braces etc
2) What is the most optimal table height? 30 inches?