Xacto saw blades that fit in the large, red handles. They have very fine teeth that are perfect on the figures.

Krazy Glue with brush for very easy application.

For joining the pieces together and filling seams, I use Games Workshop Green Stuff, also sold as Kneadatite or similar products. It's a two-part epoxy clay that dries fairly fast after combined.

Shaping tools to work the clay.

For joints that need a little help staying together, I use a jeweler's drill (basically a small drill bit holder that fits in your hand). Bore a hole in both pieces where they join and cut a piece of wire (I use paperclips) and glue it in. The added surface area for the glue to hold really strengthens the bond.

Here it is in pieces. They screw together and hold the bit at the end.

I occasionally use a Dremel with metal working bits to remove things like hair that's molded onto the body.

Various sandpapers (fine grit, like 400-800 or so) and sanding sponges.

Assorted small needle files with different shapes; round, square, etc.

Dull Cote spray from Testors for when it's all done. A couple of coats are a must.

It went from this:

to this: