I've made a randomizer before. It's not the smallest thing, but it works, depending on the type of pattern/random number you want. If you want it to be for sure only one bit at a time, or you want it to be small, use a conductive liquid/gas in a 1px by whatever dimension you want space.

EDIT: Like this. Note, I didn't come up with this :P

hey wazabi, i could help you with randomizers, i made my own one a while ago

EDIT: found a fix to column two. I commented on the creation

The one you're using isn't truly random; the wires in the middle get sparked more often. I already had to make a random number generator for another save, it should only take 15 minutes or so to modify it for this.

Edit: Enjoy!

If you add more options, it will take less than a minute to add them into the randomizer.