Crystals. She said just light, so - just light.
She gets up, puts a crystal on the other side of the ship, and walks away from it. Then she sits down (facing away from it; she's also honing her magic senses while she's at it) and begins fiddling with its fellow. She wasn't able to make an illusion of the cat under pressure. That's a weakness she'd like to work on. Crystals make this sort of thing easier, but they're not really required. But for helping her hone her reflexes, they're good. They make it easier.
Fiddle fiddle.
And then a slightly smudgy cat leaps out of the crytal on the other side of the ship, swishes its tail, and licks a paw.
The cat gets less smudged. It scratches at an itch that assumingly doesn't exist, and starts investigating the room. Occasionally it gets a little bit more smudgy, but it steadily becomes clearer and clearer. Even the shadows are correct.
For fun, Inavet adds a jingle ball, as if it dropped out of the ceiling, and takes the opportunity to practice song craft at the same time. It jingles convincingly when it hits the floor. The illusion-cat notices. The jingle ball moves as if by a wind (there isn't a breeze) and jingles a little bit more. The illusion-cat stalks its prey. Stalk stalk. (The ball doesn't move.) Stalk stalk. Butt wiggle. Will the illusion-cat pounce?
What kind of question is that, of course it will. Like so.
The bell jingles convincingly then, too. The cat even thumps as it lands on its unsuspecting jangly prey.
"Illusion," she says. (The cat smudges some more, talking takes concentration.) "Not there. Sorry."
"I meant try to touch the cat, but I'd like to try the magic too."
"Sure, to cat," she says, and the cat ambles over to Isabella and meows at her. Convincingly. Though it's still smudgy. "Magic is..." Handwave. "... More difficult," she decides. "Later, maybe. Here not good for procedure."
Isabella tries (and of course fails) to touch the cat. "What's the procedure like?" she asks, watching her hand pass through the illusion.
And if she doesn't want to give Isabella magic, she will say it's too dangerous or something. Or maybe flat out refuse.
...
"Humans have had it. Half human." She points to Isabella. "Maybe - ... not-elves could, too. Don't know."
"Vulcan, maybe, maybe not. Don't know. Humans have had it. In history. You... I don't know. Maybe?"
"Would need touch, to read you. Then time, to figure out. Might not be possible safely, but I can try."
"Nnno. Not. I can't - telepathy. Read body, read blood - understand magic function, not thought."