I'm in the middle of making an animated snarl, and need to bond a thick tab to another surface. The bond needs to be strong, but I'll then need to somehow smooth out the bonding point. What do you guys use? Are sculpting materials strong enough to bond them together, and then just smooth over that before/after hardening? Should I just superglue it and then try to put some sort of hardening putty over it?
apoxy sculpt is great for this, but you'd need to order it online, and wait a few days. I swear by super glue's fusion. It's strong as hell, and easy to use. most walmarts and home depots sell it for about $3.00 - very sandable
I use Jet medium viscosity gel superglue. It's thicker like Elmers but the strength of superglue. I also use Jet accelerator, which is a product that speed forces the cure time for all superglues, apply glue to one side, accelerator to the other and join them for 2-3 seconds. Then they are fused by chemical reaction. very sturdy and I use them for large parts as well as small delicate parts. The Fusion stuff F_R mention gets high praise too, but I haven't used it yet.
These all seem like good suggestions, so I don't think I have anything to add on that front. But I will suggest that if you can, you should try to embed the tabs into the surface, rather than just trying to glue them to it. That'll give you some extra strength, and even provide a greater surface area for the adhesive to grip on to.
Just a small note: unless it's a paintable surface you're going for, be sure to check the cure color for whatever epoxy you use. It's usually noted on the card someplace. Some epoxies cure to a really crappy color, so be conscious of that unless you're painting later.