Vault-Tec Workshop DLC is now available for Fallout 4 on Steam, providing the chance to get in touch with your inner survivalist by allowing you to create your own designer vaults to sit out the apocalypse in proper style. This is available separately (Fallout 4 is required) or as part of a Season Pass. Here's how this works:

Build a brighter future underground with the all-new Vault-Tec Workshop. Create a massive Vault and attract new Dwellers using pre-war industrial kits complete with retro-nostalgic furniture, lighting, and art. And like every good Overseer, run Vault-Tec approved experiments on your Dwellers to learn what makes an ideal citizen. Vault-Tec has given you the tools, the rest is up to you!