I love this trend of using letter light fixtures or marquee, indoors! It adds such a cool modern touch to a space, and its perfect when it is combined with different style of furnishing and decor, like vintage or modern-bohemian. There are a few companies out there that produce letter lights, like Kidimo, and more than a few DIY if you want to try- here are two that look good: via design sponge, via Brit + Co. My favorite lighting company- Delightful, has, in my opinion, the best selection of letters and numbers hands down! They really had fun with their designs! Now just pick your favorite one!
They still look good when the lights are off.