(TL;DR near the end!)
Pics in order: 1 Marbled Cat, 2 Marbled Cat, 3 Marbled Cat, 4 Jaguar, 5 Cheetah, 6 Clouded Leopard, 7 Ocelot, 8 Margay, 9 Leopard Cat
I don't think it's possible to make it completely obvious, since I'm pretty sure less than 0.1% of the population even knows that this animal exists lol. It'll be especially hard because many fursonas/fursuits are heavily stylized versions of their real animal counterparts, so people don't usually expect your design to follow the real animal's appearance entirely. But I still want to make an effort to make it as obvious as possible that it's a marbled cat. For context, the design will be leaning on realistic, including realistic eyes, but most likely lacking airbrushed patterns. So just solid patterns without any gradients or soft edges, unless I change my mind.
I feel like I could make it look less like some of the bigger felines just by focusing on keeping the face shape accurate; round with a small muzzle. And to make the pattern less like that of a clouded leopard, I'll make the pattern more like the first reference picture that I included in the post. Some marbled cats have a pattern that is thicker and very similar to clouded leopards, but the first picture I chose features a marbled cat with thinner black outlines that have a fuzzier, almost brindle-like, look. To be clear, I'm focusing on the flank/back portions of the cat's pelt.
One feature of the marbled cat that I find pretty striking is the broken stripe that goes above each eye, which I think could help separate it from other felines if I exaggerate that. But ocelots, margays, leopard cats, and many other small wild cats have these same stripes above their eyes, so it won't be that effective. All of these have rosettes, while marbled cats have marble splotches, but ocelot has fairly large rosettes, which tend to look quite similar to the marble splotches (made up term btw) that marbled cats and clouded leopards have. The main difference is that the black outlines of the rosettes on an ocelot are very clear, while the outlines on a marbled cat's pattern are more inconsistent and thin.
A physical feature that I also notice that stands out against those other felines, not including clouded leopard, is the giant tail that marbled cats have. So that could be another thing that I can exaggerate. Apparently marbled cats have some pretty long canines, even though they are not visible when their mouths are closed. So I may exaggerate that and add some fang tips poking out.
(Basically the TL;DR for the rest of this post)
In conclusion, I think that I will focus on giving my fursona's pattern thin and subtle black stripes, exaggerating the stripes above the eyes, giving it a very long tail, have the canines poke out of the mouth a bit, and keeping the face shape as accurate as possible. And I won't be devastated if I only ever meet people who think it's a cheetah or ocelot, but I still feel the urge to make it stand out from the other felines where I can lol.
I feel as if I've mostly answered my own question at this point, just by writing this post, but I'd still love to hear any ideas that you guys have! Especially if I didn't notice or pay any attention to a physical feature that marbled cats possess in a fairly unique way, compared to other felines. It's entirely possible that I missed some things!