Super7 should do Ultimates Character upgrade packs.

 While Super7 has delivered figures with decent amount of accessories, not all figures are the same... or get the same love. Mutagen Man has far less useful stuff than say, Rocksteady. Casey Jones has less stuff than Shredder, etc.

So, my suggestion is: Character Upgrade Packs.

Each would be different depending on the figure being upgraded. My focus might be mostly TMNT directed, but this also applies to Thundercats... in fact it was the Thundercats Oops we fucked up package and the Mousers that inspired this idea.

For a non-TMNT example:

Thundercats Ultimates Lion-O Character upgrade pack: 

-Stoic Lion-O head with GITD eyes

-Screaming head from Mirror Lion-O 

-Grappling Claw Shield from Mirror Lion-O

-Open "at rest" hands.

-pointing hands.

-Sword of Omens in Sight Beyond Sight mode

Maybe even a Toddler Lion-O from the episode Time Switch.

Using TMNT as another example, Let's say Leonardo:

-He gets Donatello's heads in Leonardo colors.

-Pointing hands (also useable as Ninja pose)

-kunai

-"vintage accurate" ninjato blades

-Hookswords

- 4 point Shuriken

-pizza slices

-European Sabre (but not the Wacky action sabre)

Donatello:

-Leonardo's heads in Donatello colors

-Hang Ten hands

-Naginata

-sansetsukon (3 part staff)

-smoke bombs (exploding and unexploded)

-partially built SDV from sewer surfing Donatello

Raphael:

-Mikey's heads

-palm heel strike hands

-Tonfa

-jitte

-kunai

- 4 point shuriken

-Boombox (this is a nod to his breakdancing wacky action)

-Ninja Blowgun

Michelangelo:

-Raph's heads

-Kusarigama

-chained Kunai (reference to the Yu-Gi-Oh card, not the Yellow Ninja from Hell)

-karate chop hands

-special twirling nunchucks (like Panthro)

-closed pizza box 

-Boomerang

Foot Soldier

-Katana

-bo staff

-Sai

-Nunchaku

-Sledgehammer

-Poleax

-kunai

-Tonfa

-4Point Shuriken

-boomerang

Rocksteady and Bebop

-Machete with bandolier (R)

-Arcade game gun (B)

-Judo chop hands (B and R)

-Larger trashcan shield that can fit Bebop's hands (B)

-Sawn off Shotgun (B)

-Desert Eagle-like gun(R)

-communicators(B and R)

Splinter and Shredder

-Oroku Saki Head (Sh)

-Mirage styled Helmet (Sh)

-sleeved kimono with Shredder's cloth belt (Sp)

-vintage accurate 3 finger claw hand (Sh)

-sleeveless cloth shirt with Shredder's cloth belt (Sh)

-wakizashi (Sp)

-Broken Ooze Canister (Sp)

The idea is to expand your options. Also, these packs should cost less than a figure. In the case of the turtles, the end goal is that all 4 turtles end up with 4 all vintage heads and all 4 modern heads. Which means new packs with different accessories.

For Shredder and Splinter is to "fix" some stuff from their releases and to expand. Mainly giving the missing vintahe accurate hand for Shredder and having the option for a more Mirage inspired Shredder.

This could apply to other characters as well, like say April getting her heads in reversed colors (vintage heads in toon colors whole the toon inspired head is in toy color) adding some extra accessories to make them more desirable.

As I showed not all packs have to be specifically made for a single character.