Stitching a custom IPSW with blobs

After you have SHSH blobs saved locally on your computer (using TinyUmbrella or redsn0w), follow these steps to stitch a "Custom IPSW with blobs" using redsn0w (compatible with Mac and Windows) and then restore with it via iTunes. If you have an iPhone, this method will preserve your device's baseband.

 - Open the the latest version of redsn0w.
 - If your device is an iPhone, first create a NO_BB ("no baseband") custom IPSW using redsn0w and then follow the rest of these steps. (To do this, open redsn0w, click "Extras", click "Custom IPSW", and give it a normal IPSW for your device.) If your device is an iPad or iPod touch, ignore this step.
 - Click "Extras".
 - Click "SHSH blobs" and then click "Stitch".
 - Locate the IPSW for the version of iOS you want to downgrade or upgrade to. If your device is an iPhone, select the NO_BB custom IPSW you made earlier. (You can also make a custom IPSW using sn0wbreeze if you prefer; see below for links.) If your device is an iPad or iPod touch, you can use a stock IPSW from Apple.
 - Click "Local" and select the saved SHSH blobs you saved in your computer earlier, or click "Cydia" to use SHSH blobs saved on Cydia's servers. If one of these options gives you problems, try the other option.
 - redsn0w will now begin creating your signed IPSW. It will be saved in the same location the stock IPSW was located.
 - Enter Pwned DFU mode with redsn0w or iREB. (In redsn0w, go back to the Extras menu and click "Pwned DFU".)
 - Open iTunes and hold down the "Shift" key (on Windows) or "Option" key (on Mac) and click on Restore.
 - Navigate to your signed custom IPSW and select it.
 - The rest will be a normal restore process. You should now have successfully restored your device to the iOS version you wanted.