Let's create a disguise kit. The rubber suit in question is based on DnD's Glamoured Studded Leather:
However, this item will be cursed with the following property: you cannot choose what the armor transforms into each time the Command Word is activated. For the sake of simplicity, the curse also includes a 30 minute timer to revert to its default state should the player be unable to speak, and the armor covers most of the body.While wearing this armor, you gain a +1 bonus to AC. You can also use a Bonus Action to speak the armor's Command Word and cause the armor to assume the appearance of a normal set of clothing or some other kind of armor. You decide what it looks like, including color, style, and accessories, but the armor retains its normal bulk and weight. The illusory appearance last until you use this property again or remove the armor.
Other things to add: The armor does not add bonuses to specific forms, though it can help with bluffs (aka adding spikes should not grant damage, but can make enemies less likely to attack you)
So, here are some items to start:
Default- A leather suit that covers most of the body, a bit thick around the chest. Surprisingly flexible.
Sexy Villainess- A leotard with elbow gloves, knee boots, a mask that surrounds the eyes and the top of thead, and a cape that drops down to the knee. Mostly black, inside of cape is red.
Cat- Two triangles form at the top of the head and a belt extends out as a tail. The ends of the gloves become more pointed. Usually forms with a domino mask, and usually black in color.
Blacksmith- A leather apron and a pair of pants, held up by a massive (and empty) tool belt.