Now go to View > New Guide (twice time) and add horizontal and vertical guides with 0 px in input box.
Duplicate this action, but instead of 0 px type in 100% (you can determine guides not only with pixels but also with centimeters, inches or percents). You will get the following:
Then go to Image > Canvas size and type 10 milimeters in each field (because this is the size of margins). Make sure that Relative checkbox is checked.
And again, add guides the same way. Here's a tip: You can record a guides adding process as a Photoshop action (for you don't have to type a specific values, just a beginning and end), so it will be even faster.
And at last go again to Image > Canvas size and type in boxes 6 milimeters, for this is the size of bleeds. As you can see the values are relative and always the same, and by that universal, so you can make a one huge Photoshop action to fasten this process.
Here, I have even prepared one for you. While playing this action you will get a dialog box four times. Just type100% in the input box and hit [Enter] each time. That's all. The easy process becomes even easier. Of course sometimes you will be asked to make bleeds of some other value than 3 mm, so you should also remember the process.
Margins&bleeds.atn | 1,5 KB
Step 5 - Stop that talk, start design!
All right, it is all for today's dirty work. Hopefully some of you have learned something. Now we can go straight to the design part. Do you remember what we are actually creating? I am scared that I confused you with that business card's talking. So we are making a tri-fold A4 brochure, here's the specs:
And here is a 3D concept to make it easier to understand by you.
Have you noticed something? When you will leave bleeds you will get the following sizes of each pages: 208 / 211 / 211. Why this bold dimension vary from others? It is just folding aspect. The page that is shorter just need to hide itself inside the fold. And if its size would be 211 mm (as rest) it could not fit into the fold and make paper blobs on brochure. So by getting those two or three milimeters back you will avoid those potential troubles.
All right, we can start work from here, really. First of all- create new document with a real dimensions lowered by 10 mm from each axis (because of margins) - just follow the Step 4. My bleeds are equal to 2 mm, not a standard 3 mm. But actually I can run my action, and then just go to Image > Canvas size and type -2 mm (-1mm × 2) in each input field (remember about Relative checkbox).
Now we have to create some additional guidelines that will determine folds. Here's a trickery. We have to make different guides for inside and outside part of our brochure. Look at this sample guillotine work:
First of all, I will tell you how in Photoshop delete already made guides. It will help you if you will set them wrongly by a mistake. Ok, here's a magic- press [V] or choose move tool, click on a guide that you want to delete and drag it outside the document- it will disappear. If you want to rotate your guide by 90 degrees you can just press [Alt] and click in the point where guide should rotate. If you want to move guide by 10 pixels and it's multiplications do it while holding [Shift]. Now let's create our folding guides. Go to View > New Guide and type in 213mm in the input box. Repeat step, but with value of 424mm (213 + 211). Save the document as a inside.psd. Now delete both guidelines and add another two, but now type respectively 210mm and 421mm (210 + 211). Then go to File > Save as and save this document as outside.psd. Now we will start to work with this outside.psd document, and inside.psd will stay untouched as grid-only blank document for now.