Inspired by the theme recently shared by @Ben Ling, here is the pattern-lock screen...with Lego!
To do this yourself, you can download the icons attached to this post and put them into the appropriate drawable-?dpi folder in your decompiled framework-res.apk.
Or, if you're not comfortable with decompiling apk files, just flash the attached 'Lego_PattenLock_Flashable.zip' in CWM (not TWRP). This zip will push a file called 'android-res.apk' into your 'system/vendor/overlay' folder.
By using an overlay apk, it means that your framework-res.apk isn't touched. So you won't lose any of the mods you may have done to it. Pretty cool, no?
Oh, and this zip will make a flashable backup too! Just in case you don't like the changes. Also pretty cool.
(Or, if you use Tickle My Android, why not just let the tool do it for you? I've just updated it with these icons!)