Click in the menubar on File --> New --> Blank Disc Image
Fill in "Save as:" field with a name.
Select an appropriate size.
To calculate an exact size:
Open the folder whose contents you want encrypted.
⌥ ⌘ I to get collated info on all the contents (minus the folder itself)
Note down the exact byte size and enter that into any online bit calculator (ensure you've selected bytes, not bits and that notation type is kilo/1024).
REMEMBER, whatever you specify includes the encryption and DMG info so the ACTUAL empty capacity will end up a small amount LESS than what you specify.
So get the kilobytes figure from the website, multiply up (to "recover" the header info space) and then round up to the nearest whole number.
Enter this figure into the space allocation
Set the encryption to AES-128
Keep the format as "read/write disk image"
Click "Create"
You'll be prompted for a password - enter one
Very important: Unselect "Remember password (add to Keychain)" before clicking OK to set the password.
Finally:
For that "extra" bit of anonymity, after moving everything you need into the dmg (to check it fits) press ⌘ I and check "hide extension".
Now, open Pixadex/Candybar and replace the standard dmg icon with a custom "locked folder" icon/system folder.
Remember:
Encryption data and header info takes about 22MB.
