Made an XNOR Gate (3 by 2 by 4 blocks), no Comparator.

I have built an XNOR gate from scratch without comparators.

To make the wiring more compatible, I used a target block, as an incoming redstone line would redirect the dust. Target blocks can be removed and replaced with normal blocks, depending on the input direction (if activated by a torch from underneath or above, they can be removed).

It's only 2 main blocks long (there is a torch for the output, so this would make it 3 long, but this can drive a wire underneath it, so in a way it's no longer than the redstone output collecting wire; this is why I put it as effectively 2 long), 3 wide, and 4 high.