Here's an occult summoning circle for dressing up paper props. It's intentionally clean so you can distress it as required. Just right click and open the link in a new tab to download the full sized version.
Below the base version are two different takes on how it could be used. The first is how it would look tinted by watercolors on parchment. The second the "energized neon" look popularized by the Arcane Circles Photoshop brush set from ObsidianDawn. I've been surprised by how widespread this style of presentation has become over the years, to the point that it's been adopted by Marvel in their upcoming "Doctor Strange" movie.