I tested Achronicity's updated version of "Kasa for A3", a set that morphs Aiko's feet into paws, either plantigrade (flat footed) or digitigrade (standing upon the toes). This beta has more features, like morphs to scale the toes, spread them, or even "square" the knuckles. It even has morphs for built in claws, even one to retract them. It's not publicly available at this time. But if you contact him at Fur Affinity, he will probably negotiate a deal with you. I think he is selling his stuff on a "one on one" individual basis now rather than through an on-line store.
Anyway, in addition to the toes, I experimented with the fingers. There is no dedicated product to affect the fingers though Capsces' "Furries for...Melody" which uses A3's body has some dials to tweak them. However, I just toyed with them directly, making the last and middle segments of each digit shorter and "fatter". Messing with the innermost segments distorts the hand. Meh, the final effect is "passable". At least the fingers no longer look "elven".
That got me thinking about claws for the fingers. After I made this render, I got an idea. I loaded the "gloves" from the A3 CatGirl set (inspired by Felicia of the "DarkStalker" videogames). I turned the "gloves" material zone "invisible" which revealed the built in claws. I conformed them to M'ress and then adjusted all ten of the gloves' last finger segments making the claws poke through the tips of A3's now stubbier fingers. I applied a few subtle poses to M'ress' hhands and so far, the claws have followed and remained in their adjusted positions. I might convert the claws into "props" and simply "parent" them to A3's fingers. I'm not sure which might prove the more stable solution.
As usual, here are the credits.
Body textures...Daio and Verge Visible
Face and body morphs...Beth Capsces
Tail prop...Little Dragon