Im getting ready to make some myself. 3' x 15' tables, two of them.
I purchased the metal corrugated sheets because it seemed much much stronger than the plastic corrugated sheets at Lowes.
I also bought some gutter. I was going to add the gutter on the low end, the 3' section, and I was going to do a 4 inch decline from the front to the back of the 15' table.
Is 4 inches decline too much for a 15 foot table? And is there any real benefit to running your gutters along the length of the table instead of the end? I would prefer to put them on the end of the table because I wouldnt have to be working over a gutter the entire time I'm working on the plants.