I wanted to make a grid to lay up 32 cm (1.25") squares with a space of 1 cm between each square. The Photoshop Help was no help, so here's what I figured out to do in Photoshop (this assumes you know the basics about Photoshop as I haven't gone into complete detail):
- After much trial and error, and being decidedly mathematically challenged, I created a new document 35 mm by 35 mm. (to get about 1 cm of space betweeen the squares)
- I went to: Select » All
- I chose Edit » Stroke. For Stroke, I entered a value of 1 px; in the Color box I chose black, because I wanted to be able to easily see the gridlines. For Location I chose Center, then clicked OK. I then created a second line using the rectangular marquee tool to create a marquee 1 cm inside the edge & again Edit » Stroke (using all the same selections in the dialog box.)
- I chose Edit » Define Pattern and named it 35 cm grid, then clicked OK.
- I created another file that's 8 1/2 x 11 and 300 dpi.
- I created a New Layer.
- I went to Edit » Fill, chose Pattern, then chose my pattern. (Under Blending the Mode is Normal and Opacity is 100%)
- I then manually centered the image on the page.
- Choose File » Print. I got a notice that the image is larger than the paper, but it doesn't matter how it crops since the image is centered on the page.