How do I create 1 pixel grids with differing colours on my own?
For example this 960px_12_col_grid:
Better visible: : http://i.stack.imgur.com/5cryP.gif
You can always create it in Photoshop by drawing the first part and then copying it to the whole width. The other question is of course, how do you intend to use this grid?
This is relevant when:
And one more suggestion. It's usually wiser to create a Npx x 10px images instead of Npx x 1px, because browsers will render it faster, and file size will be almost the same. At least with this kind of images.
Use marquee tool.