9 of these devices stacked in a cube in this example. It can be expanded infinitely.

This is very useful for redstone screens, as this doesn't take much space. From the changing of the clock, to the changing of the output takes 4-5 ticks. Sadly I had to use a number of repeaters, which was unavoidable.

The hard thing about 2x2 tileable circuits is that there are a ton of connections that you just can't make. To change horizontally, you have to use a torch. You can't place an upright torch, nor can you power a wire on a different level as the torch itself. You must use a repeater to change vertically. You need to be very careful with single pieces of wire, etc. It just wasn't easy.

It's pretty easy to build if you take the images as reference, so I hope this is useful to someone. :)

This was made on the Redstone Development Foundation (RDF) server, the server designed for redstone developers.