For the materializer may be better to have the reference card I/O side limited to just the + marked side on the texture, and have the materializer/writer I/O sides on all others.

Currently its piping configuration is the same as the proxy. The proxy logicially behaves in a manner somewhat opposite of what the materializer does. With a proxy, You'd normally want to pipe in/ out the reference card (top GUI slot) and with a materializer, you want to pipe in/out the written card.

Ok, experimenting more with the materializer and proxy leads me to make an different suggestion.

Proxy's Read slot should be associated with the top and bottom faces, and the Write slots (but input and output) should be associated with the sides. The Write input slot shouldn't allow items to be pulled from it.

For the materializer, its vice versa. Read slots are on the sides, Write slots on the top and bottom.

Ideally, all of the sides should be configurable like with EnderIO machines, but the setup mentioned here should be easier to implement and is similar to Minecraft's behavior with furnaces (input at top, output at bottom, fuel in the sides)

I'll leave this for MC 1.13, to avoid existing automations to break.

I'll rework the I/O sides for all machines then.