I am a solitary eclectic witch, and lately I feel like I want to shake things up a bit with my monthly rituals/esbats. I'm of the mindset of "if you're bored with your ritual than God/dess is bored with your ritual". I was listening to a recording of S.J. Tucker doing a live performance of her song 'In the House Of Mama Dragon' (the song is about one of her mentors, Trudy) and she mentioned somewhere in the middle of the performance that Trudy holds a Looney-Tunes themed ritual every year on the full moon falling closest to April 1st. And I thought to myself... that sounded like my kinda thing, y'know? I'm sort of a kid at heart, and sometimes I have trouble being solemn and meditative through an entire ritual. So I thought maybe sometime soon I would plan a ritual with a laid back, silly theme, probably something pop-culture related. Some of my ideas for themes are steampunk, Alice In Wonderland, sci-fi, superheroes, Harry Potter, Lord of the Rings, Skyrim and Zelda. I won't be doing these kinds of themes all the time, just enough to keep things interesting for me.
I'm not afraid of trivializing it... at least not too badly... It's made for me and will still incorporate something that's meaningful to me. I'm a pantheist (at least I think that's what I am) and I believe that no matter what name I call God/dess I'm still referring to Them (even if it's not a deity's name), and I'm also pretty good at spotting Archetypes in things, so I think I could easily find where the aspects of myself, magick, my guardians, my guides and God/dess appear in these themes, therefore including them in my rituals like I normally would. What I would really like is some tips from people who have done this sort of thing before, and maybe an example of a ritual I could take some elements from.
I'm not sure how much help I can be because I don't actually practice pop-culture witchcraft but I'm the same with being playful and fun with my practice. I like to mess around and not be too serious. Especially if you're into chaos magick theory there's so many options. Although I don't tend to do large pre-structured rituals and like to practice on the fly, the way I would suggest to about creating a themed ritual would be to start by spending some time learning the details and intricacies of the theme then meditating on it and choosing which parts make you feel the most fizzy. Then you'd take these parts that create magick within you and build the ritual around that.
For example, with Harry Potter it's the different creatures that I get most excited about, especially with the Fantastic Beasts series currently. With that in mind I would take some time to write about the creatures, their potential connotations and potential magickal implications. A way to incorporate these in to my practice could be to perform a visualisation in which I call upon aspects of a creature in the same way you might a deity or other archetype. It might be fun to create a thoughtform of this creature and get to know it that way, which could then lead to it being useful in the future. Spells from Harry Potter could also be adapted for real magickal use, and imagery (and food!) from the series would add to the fun of the ritual, as well as helping to call upon the energies you're playing with.
It sounds like you're wanting to call upon deity specifically through these themes so a more obvious way to go would be to look at the characters from the theme individually and pick out aspects that you feel represent the God/dess for you, then using the imagery from these characters to call upon those aspects.
I know this isn't a full ritual, but I love being fun with magick so I hope it gave you some ideas :)