Okay. Since you're not picky, here's what I have in mind. All banners can have day/night mode. Depending, I can make 2 banners, or lately I've been making lighter/darker ends of the same banner with shifting focus.

UFO I was thinking these two images:
https://i.pinimg.com/originals/ef/de/f6/efdef6ad5be4a8781e93ccfb592df8f1.jpg - or maybe one flying from The Day The Earth Stood Still (1951)
and a variation on the poster: https://www.themarysue.com/wp-content/uploads/2016/04/main-qimg-6b8ef4718a4a08ba19f338bc9602e787.jpg

A montage of metal images, from rust to brushed chromium, from rivets to engravings - somehow yet to be determined. Metal and BlackMetal may be the same - but with different titles. It's funny that I'm doing this considering I don't like the music much. Of course there are some exceptions. If you happen to know anyone who does a good Metallica impression and/or can play acoustic guitar, etc and/or know of someone who can - I would actually animate a music video for a raspy mellow angry "The Unforgiven"/"Nothing Else Matters" styled cover versions of "All The Things I Wasn't" and/or "Ship Of Fools" and/or "The Weeping Song" and/or "I Lived On The Moon". Man, if I could do that style I'd cover all sorts of shit.

I don't know about cats. yet. I might use part of this old design I did. It's vector so it can be any size, any colours, so that glimpse is just all that the archive.org captured a decade ago. I'm also tempted to do a montage of pretty cats. But really, I'm thinking something more stylish. Like the /s/Sex banner - but with cats somehow.

I actually fixed one of the things I have to do to the CSS today. More still to go. I'll apply the CSS's after I finish fixing the CSS for good (hopefully) and add the banners if ready or later so I don't make extra work for myself. So CSS is first. I also have a dozen or so banners I want to do for my own subs too. That will be my reward, after the CSS is done.

After they're done I can stay or go as you see fit. The CSS may get updates in months and years to come. I have no interest in moderating (even my own subs). Lemme know if you wanna be mod of any of mine. Also, FYI, I've recently discovered multisubs. They're also a good way to keep tabs on your fav subs without adding and removing them. Also good for moderating.

I started this wiki recently but it will be a while before the entire SaidIt is categorized. https://saidit.net/s/SaidIt/wiki/multisubs Of note, there's one called "Carswell" for all my subs if I ever want to moderate or keep up with what folks are posting there. As I'm co-mod I'll add your 4 subs too and remove them when I leave. Personally I like SaidIt_SaidIt best - for just SaidIt-related stuff - but there again, I'm always behind.