Something that's always put me off when it comes to furry costumes is the obscenely large heads and baggy limbs. So I was thinking that instead of default limb sizes, which include the heads too, you could decrease and increase the size of each part of the body and even edit the mesh. A good example of what I'm looking for is in the pictures below:

As you can see, the user has a face sculptor open, which shows the wire frame and also more basic editing tools like part shape and size.

Pictures are from RaceMenu by Expired

Currently, each embellishment gets 4 sliders; Size, Tilt, Twist and... more twisting I guess? Not really sure what the 4th does to be honest.

I suggest 3 more; X shift, Y shift and Z shift. X and Y shift are just to nudge where you placed an embellishment, and Z shift are to rise and sink an embellishment into the avatar's body.

Say you want the horn but not the nub on the base of it? Just sink the nub into body with the Z shifter and use X and Y to correct the horn's position if that throws off where you wanted it!

Want body parts barely floating near your character's body, just like in your favorite anime? Just use the Z shifter to rise the embellishment off your character's flesh! It's not weird! It's not weird at all!

I would like to have the ability of letting a tentacle makes its way through the gastrointestinal track, starting from either end, and that would be pretty cool if this game has that feature.

Inserting a characters muzzle into another's pussy/ass

If any of you have seen that one H0rs3 webm then you might want to see this in the game

i think you should add in-game cheats like in rack 1 and allow mod support

okay so i thought it could be interesting if there were "real animal" mating. there could be many different animals that would need a type of breeding stand. though the point is that you cant control the animal in question more than what hole to use so to speak. once it was started it would be no turning back until the action was complete, speed and length of each animation could be random for a better individuality. this could also be a late game store item where you first would need to buy the addition of a barn to keep the animals in then be able to buy the different animals and different breeding racks. you could possibly also use the breeding racks without the animal.

Basically a gloryhole room that uses the portal mechanic from the first rack to connect 1-5 male or herm subjects at a time

Introduction a TF mechanic? Where a slime/goo/latex like liquid can be genetically coded and stored until a human or a furry subject is selected to be the host.  The user can choose whether the host maintains their consciousness and personality, or be replaced and took over during the creation phase of the organism. Also, the user could choose if the organism is infectious or not, meaning the user or the other subjects could also experience this kind of a gooey madness ;).  And then after the organism’s first creation (if the user chose that it has its own consciousness), it will overwrite the host’s physical and emotional stats (i.e. gentle treatment during research and the outcome would be a loving, friendly new personality, if the player rushed for progress & achievement and treated the slime harshly, then they might despise the player and would not cooperate or demand high payment, etc. but negative traits can be eventually canceled out with each ♂♀ if you know what I mean).  But yeah just thought this would be fun but at the same time pretty hard and challenging to implement (?) Anyways let me know what ye think eh? :D

A system where a mind controlled test subject will want to stay forever. Perhaps you can use their rack like furniture, placing them for public use. Maybe there could be a sleeping system to accentuate this. 

Maybe this could work with the possible material transformation fetish. A character that is turned into latex could be fashioned into actual furniture. Or possibly sex toys and clothing. A butt plug can't ask to leave after all...