Another We need a Super7 Ultimates Karai Figure.

 Karai, the literally Spicy ninja, daughter of Shredder, was introduced to TMNT Lore in 1992. The vintage toyline was still going strong by then. For whatever reason she never made it as a toy. She has become a key player in TMNT lore and has appeared in other toylines, except for the Original line. The good news is that Super7 has the opportunity to "correct" said mistake with the TMNT Ultimates! Line.

In the past I have made suggestions on how Katai could be doable by mimicking the Playmates style with a Mattel-like twist since the better articulation allows for mixing and matching parts in ways that the original line could not. Not today! Today I want to go out balls to the wall on making a proper 1992 Karai...

There are 2 options for Karai. Either using the outfit with the bulky jacket or the bodysuit version. The bodysuit version is the easiest version since she's in a bodysuit and the FourHorsemen probably have a "naked buck" template that they can use.

Using the jacket version would mean taking the "naked buck template" and adding the clothing details. From an unbiased point of view, this would be the best way to approach Karai. My preference would've been the bodysuit with an optional jacket, but the jacket wouldn't look as good as if it was made as the default option.

Now can parts be reused from April? In a Worst Case Scenario, hands and feet. Personally, I'd take 100% new sculpt on her. For her accessories, extra hands are a must including hands that can hold arrows. Second head without her foot clan bandana. Now is when we look at the vintage line for accessories: Namely Movie 3 April and Princess Mitsu:

April's Ninjato, with Mitsu's Bow, Quiver and arrows are a nice start. Make a second ninjato, add a couple of kunai and shuriken to complete the accessories.

I'm jumping over one important thing: Color scheme. Her outfit is usually purple or fuchsia on Mirage related art or her first videogame appearance. Personally, she should implement the toy Foot Clan color scheme: purple, black, blue, and grey. Using the Foot Clan color scheme and the Jacket look for Karai, I'd go for:

Black pants and sleeves. The wraps on wrists and ankles would be Blue. The Jacket would be Purple with her belt, pouches, shoulderpads, and buckles in grey and silver. (Silver for metallic accents and grey for everything else.) The toyline has had a precedent for deviating from Mirage colors to more toyetic colors. 

Now how can she fit in on the toyline? She'd be in her early 20s for the sole reason of her being young enough to remember her father leaving to America to exact revenge on Hamato Yoshi "for dishonoring the Foot".  Raised by the Foot's Blind Master Hattori Tatsu. Being a Ninjitsu Prodigy, Karai rose through the ranks.  Eventually challenging Tatsu for control of the Foot Clan and beating the blind Master in combat. Once defeated Tatsu revealed the truth to Karai about her father. Angry at her father's reliance on Krang, she seeks to take down the Evil Overlord of Dimension X to restore the foot Clan's honor... or something like that. She's loyal to her father's cause, but distrusts Krang to the point that she has a shaky alliance with Hamato Yoshi's clan to take down Krang. 

She brings a shock to the power dynamics at the Technodrome. 

Karai hates Krang for "corrupting" her father.

Krang suspects that Karai is not what she seems.

Shredder is happy with using both Krang and Karai to fulfill his goals.

But the most important part is getting a figure of her. Especially since she would be a HUGE surprise as a core character that didn't have a vintage toy. I'm sure folks would rather have Karai than Shotae.