I agree with this suggestion to print, cut out, and tape to another ring. Remember even if on another ring you won’t get the full 3D effect.
A 3.5 carat ring in a cushion or princess will be different “face up” than a 3.5 carat in a round.
I have a 5.25 – 5.5 finger (though wear larger sizes for wiggle room and comfort when my finger swells in the heat) and my personal daily wear/wedding ring “max” for rounds is 2ct (8mm), which is actually what I have (in moissanite). Personally, after that, I find it looks a bit space-ship-like or door-knob-like (on ME personally). For other fancies, it can range between 1.5ct (a pear or marquise for example at that faces up larger than my 2 ct) to 3 ct (such as certain step cuts that carry most of their weight in their belly). A 3.5 ct cushion or princess (and definitely a round!) would generally be too much “for me” but that is just due to my own personal style and the aesthetics I prefer in rings.
Everyone has their own sweet spot though. Some women really like a larger, flashier, ring for everyday, and others would find it too much like a cocktail ring (meaning for these purposes a “special occasion ring”) for their own daily wear. For me it depends so much on your own personal style (understated, trendy, natural, fashionable, flashy, demure?), your overall hand shape (not just finger size!), whether it is in a halo or not/setting choice, comfort level (how do you feel about attention, or fitting in with those around you, does a large ring “match” you, etc), rings of those people around you (if your friends have 0.5 ct rings, do you feel comfortable with one much larger?), your actual lifestyle (are you more likely to be out training for a marathon, or hanging with friends drinking martinis?), where you work (do you work with disadvantaged groups, or in an unsafe area?), whether you will expect to wear the ring 24/7 or not (while IMO opinion ALL rings need care and should not be worn 24/7, larger rings and more delicate settings will need even more care) , and so on.
Also, since you are going with moissanite, it is important to know whether you intend to “pass it off” or not. I have moissanite, and am honest about it, as I love it so, but I recognize many do NOT want to say they have a moissanite. If that is the case, you want something that is going to be more “under the radar” and will be something that others would “expect” you to be able to afford. If your life/budget is more of a 0.25 carat one, showing up with a 3.5ct ring (even if they don’t know exact carat size other than “huge”) might attract more questions. Only you can decide how comfortable you are with that.