The Archangel Michael is one of those entities whose spirit moves across many religions. He is invoked by Protestants, Catholics, Jews, Muslims, Pagans, Witches and many others in between. Universally seen as a helper and protector, he is the original "guardian angel" and is always willing to help when asked. A tiny bedroom shrine is the perfect way to request his protection from the unseen dangers that lurk in the dark while we sleep.
St. Michael, which I got when I visited my mother the last time. Cards like this are available from Catholic gift stores, some churches (the Roman Catholic cathedral church in many cities is often dedicated to St. Michael), metaphysical shops, botanicas selling spiritual supplies for Hoodoo, Santeria, Voodoo and other African diaspora religions, and many online stores. (My local metaphysical shop literally can't keep St. Michael images in stock because they sell out almost as soon as the shipment arrives.) For the shrine case I was going to buy a plain wooden box at the dollar store, but I couldn't find anything the right size. I could have made it out of foamcore (a great material for these because it's so lightweight) but instead I decided to adapt something I already had, a miniature cabinet which was ugly and the wrong shape, but exactly the right dimensions.
Red and blue seem like good St. Michael colours (and red is a traditional colour for shrines, especially in Asia), with of silver trim seemed to invoke his protective sword. I tried painting it with metallic silver acrylic paint, but it didn't seem very sharp, so I used aluminum tape instead, which was much better.
You need not fear the terrors of night,Some Pagans are uncomfortable with the use of Bible verses in spells, but there's a long tradition of it in both European and American magic. I see the Book of Psalms of the Old Testament as really just a collection of ancient Jewish spells and charms whose effectiveness has been enhanced by thousands of years of use. (The classic text on the subject is Godfrey Selig's 18th c. book The Secrets of the Psalms.)
The arrow that flies in the daytime,
The plague that stalks in the dark,
The scourge that wreaks havoc in daylight.
Grain of paradise is an African pepper-like spice whose use in European cooking is long forgotten but remains in use in American Hoodoo magic, and adding it to "activate" St. Michael images is one of its uses. (Seven is a good number for protective magic.) The grains of paradise and the Psalm will be hidden when the front is closed, but they don't need to be visible to work.
Instead of St. Michael, a little shrine to Kwan Yin would be equally beneficial for protection from night fears. In that case I would make the inside white instead of blue, and perhaps decorate it with tiny pearls. A small incense burner would be a good addition, too. There are some lovely prayers to Kwan Yin here.