Green stuff OR milliput. Green stuff, to my knowledge, is a bit harder to work because it's very clay-like, whereas super-fine milliput is much easier to force into gaps in minis and is easily available on amazon for like 8$. A big advantage of milliput is you can add a little bit of water to it after you mix the two part epoxy to make it a bit slicker and even easier to get into gaps/blend, and it'll dry just fine regardless.

https://www.amazon.com/Milliput-Superfine-2-Part-Hardening-Putty/dp/B002CNEWAM/