Red I need your help! Can you create a custom build for a plugin im building?

Hey, well, basically we have three options here

On the one hand, I could add a setGuiElementColor() method to the Internals class. The method is already there, it's just not yet exposed to the API. This enables you to change the color of an existing UI element. If you need a big preview, you could double click on the element and change the color of the fullscreen-background to green. That would look like this:

The code for that is simple, it would be something like this:

@EventMethod
public void onCommand(PlayerCommandEvent evt){
    int playerID = evt.getPlayer().getID();
    if(evt.getCommand().startsWith("/greenscreen")){
        Internals internals = getInternals();
        internals.setGuiElementColor(playerID, "CraftingFullscreenBackground", 0x00FF00FF);
    }
}

As mentioned, this doesn't work yet, since this method isn't exposed to the API, but it would work after the next update.

The downside of this is that you have to double tap on the preview in order to enable the fullscreen preview.

Option 2 would be to set the crafting background invisible, and add a green panel at that position. You also have to move away the variation increment/decrement buttons. That would look like this:

This would be the code for that:

@EventMethod
public void onCommand(PlayerCommandEvent evt){
    if(evt.getCommand().startsWith("/greenscreen")){
        Player player = evt.getPlayer();
        Internals internals = getInternals();


        internals.setGuiElementContentVisible(player.getID(), "CraftingBackground", false);
        internals.setGuiElementContentVisible(player.getID(), "CraftingPreviewImage", false);


        //We cannot make these elements invisible, since changing the item would
        //make them visible again. So we just move them away. You can still use
        //your arrow keys to change the variation
        internals.setGuiElementPosition(player.getID(), "CraftingVarInc", 0f, -1f, true);
        internals.setGuiElementPosition(player.getID(), "CraftingVarDec", 0f, -1f, true);
        internals.setGuiElementPosition(player.getID(), "CraftingButton", 0f, -1f, true);


        //Create a new green panel and attach it to the crafting background
        GuiPanel panel = new GuiPanel(0f, 0f, true, 1f, 1f, true);
        panel.setColor(0x00FF00FF);
        panel.setAlwaysInBackground(true);
        player.addGuiElement(panel, "CraftingBackground");
    }
}

Again, this will not work before the next update is available. The update is almost ready, I guess it will be available in 1-2 weeks.

Option 3 would be to just use renderings of the objects. Objects are rendered "on the fly", but there is a renderobject command available. Unfortunately it's broken atm (resulting in wrong colors), but we'll fix that for the next update. The downside is that this command only works for objects (e.g. furniture), so you would have to retrieve the item icons from the game files.

Please let me know if one of these options would work for you