Plugin webpage: https://codefling.com/plugins/building-skins
The Building Skins plugin allows you to use the DLC Building Skins without owning the DLC’s. To use these skins, do the following:
Use the /bskin command to switch modes. This will open a window like the one to the left.
To update the skin for existing building blocks, you need to activate the skin and hit the block with a hammer. The block will be updated with the selected skin.
To change the skin for all buildings using the /bskin build or /bskin all command, you need to select a skin mode. Depending on the mode you choose, the skin will be updated.