I tried that already a little bit and try how it will effect the game. But a Oredictionary for Facade and a Function that allow that you can list of all Facades (because getSubItems is only client sided).

Also a bug: If you place a pipe above a block that requires sunlight and place a facade on the top or bottom the (in this case solarpanel) still resives light. I do not know if this a feature or a bug. I will show it in my next world tour.

There is no true list of all facades and probably won't be. If anything, a list of all recipeable facades, as you can theoretically make a facade out of any block.

True. I do not think there is one needed. Unless Facades support oredictionary. ^^" I am still testing it in my mod if it makes sence or not.

Also i have a block that allows to change blocks/items in the oredictionary (config with black and whitelist also there),
but the main problem is that there is no serverside function like: getSubItems(). Because the Items/Blocks get stored with no MaxMeta. Simply its meta (Short.MaxValue) and you have no clue which one can be used and which one not.
At the moment i simply use for that the client function getSubItems() which seem to work on a server (a bug maybe from forge).

I think was a to big explaining.

A little question did you see the bug with solar panels and facades @Asie

adding it as oredictionary would be trivial i think, just register the facade in the oredictionary under "facade" or something like that

true. But i am testing it with a block that allow it to choose any item with the same name in the oredictionary. Simply i can make out of dirt Facades electrum facades. If they exsist. And the thing is if there is a uncrafter for facades then it can quite distroy the gamebalance.

Decided against. Just use the GameRegistry or Item.itemRegistry.

Yeah ok.

Note @asiekierka, your suggestions with GameRegistry and ItemData wont work.