Materials for tail creation?

Hey!
I've never worked with silicone before, so hopefully someone else can add their input.

I made a moveable tail, but it's a permanent mod to the doll now.
So I used some plastic doll armature from Morezmore. It's sturdy, but not too heavy and has good range of movement.
I secured it to my doll with apoxie sculpt, right above the booty.
I covered the tail with fabric and felt on the tip, for fur-like effect. (He's a dragon)

If you just use the armature, I'm sure you could cover it with something to achieve the look you want. Hope this helps!

 

I haven't made a tail like that for a bjd but I did for a plush, though the tail would probably fit fine on a 1/6 bjd. Mine is a wire frame, faux fur on the tip, then I wrapped the wire frame with batting and sewed stretchy material around that. For your tail end, you can probably sculpt the little heart end shape in clay and attach that to a wire frame. I'm certain you could find a flesh tone fabric as well.

Here's some pics of the finished tail I made for reference~

Spoiler

 

My first thought is like yours, to have an armature inside a silicone etc tail. The silicone is doll safe in general.
But, if you are farming for alternative ideas I feel like you could sew one, stuffed and armature'd out of a non-fur material like leather, faux leather, even other certain thick stretchy dancewear fabrics. I think the benefits of these over the silicone (provided you can match the color you want well enough) are that they will be more durable over the years to movement (faux leather would be my last choice because of deterioration but I think it would still last in a pristine form longer than silicone) and that if the tail needed repairs later to the armature you could get in there to replace it and sew it back up again.

 

Silicone is doll safe - kips disks are silicone, too

If you feel like that's the material that has the best feel for your project go for it! It's not difficult to cast (into a plaster cast for instance), but it is a little pricey in larger quantities. You can cast it with an armature inside right away and then just trim the seamlines and voila.

If you are ok with a less soft tail, polymer clay or 3d printing are good options - much cheaper/easier than resin casting.

 

I'm not sure how much posability you desire but foam is a fun option if you want something you can hold, and pull, and squish! A friend of mine recently made a cosplay tail using blocks of squishy foam encased in a sewn fabric cover. It was solid and flexible. And squishy!

 

You can also make casts and pour foam if you want to go the fancy way - I had good luck with the FlexFoamIT and plaster casts.

 

In addition to the ideas already brought up, amature stop moton animators often make puppets using an aluminium wire "skeleton", foam of varying densities to simulate muscles and soft tissue and then cover it all in a latex skin. The latex does deteriorate over time and will need replacing eventually, but it can be cast using a simple plaster mold, so redoing it is not a huge job. It's a lot less toxic to handle than silicone and can be painted using tinted liquid latex. The only fumes it gives off is a bit of ammonia while drying, so you need good ventilation, but normally no mask.
I do agree with the others, though, about silicone being perfectly safe for contact with dolls.
As long as it is properly cured, is should not leach anything and it should not deteriorate much with time (it will wear out with movement). The downside is that is is nearly impossible to paint, so you will have to cast it in the right colour from the start. There are silicone "make up" paint that can be applied to the surface (used for things like reborns and other silicone dolls and for masks and other special efects) but that will wear off with time and can transfer to fabrics and probably also to the doll itself. Glueing things to silicone is also very dificult, (and toxic) so you'll have to plan carefully and make the whole thing in one piece. The rule of thumb is that the only thing that sticks permanently to silicone is silicone.
If you have no vacuum equipment for casting you'll have to be ok with minor bubbles, but if the silicone is pigmented to a near opaque colour, they souldn't be very visible.

Both silicone and latex have a bit of a learning curve to them, so be prepared to make a few versions before it's perfect.