I model in 1:24ish, but this will work in any scale that the figures are available. The cheap Chinese figures off of ebay are what I'm talking about. I finally read somewhere that these things are ABS plastic. They come in lots of shapes and sizes and poses. But, I always need a different pose it seems. So I bought a bunch of figures and use them as 'spare parts' for making what I need.
I needed a pilot for a current project so I thought I would document how I do this and maybe it would help someone else. I've seen people complaining about these figures but I like them. They are easy to cut, glue and modify. My main surgical tool is a razor saw, with backup from an Xacto knife during the finishing process. I use ordinary styrene glue (Tamiya because it is what I have) and it works great.
You will see that it takes hardly any effort to do this, just a bunch of messing about with bits of plastic. I save all the sawdust, and bits that I saw out, using them as filler as necessary.
Here's a couple of volunteers waiting for surgery. In this case I needed a sitting figure with his legs sticking out more than down. So, I chopped up a standing guy for his torso and a sitting guy for his legs and added an extra head from Egor's spare pile.

The standing guy is necessary because of his arms, they can be removed and repositioned and reshaped.


Here is the carnage after the first round of surgery. Both figures separated at the waist and arms removed from the standing figure.

Then the sitting figure gets his pelvis split to allow his legs to be spread. I also cut a notch at the back (butt crack area) to allow the legs to be properly spread out.

The plastic isn't what I could call brittle, but it doesn't bend well. I went ahead and separated the legs at the center line since it will happen anyway during shaping. Here we have the knee work. Cut a wedge from the front of the knee (aren't razor saws nice? ) and it will be used as filler at the back of the knee to straighten the leg.

In this case, both legs will be done the same way.

The legs have been straightened, wedges installed at the back of the knee and glued. I put a generous drop of glue on both surfaces and then push them together. The plastic gets rubbery and can be manipulated for quite a while after gluing. I use the cut out pieces as well as the saw dust as filler. It becomes soft in the glue and can be smeared around with the tip of the Xacto knife.

"Off with his head" said the Queen... and it was done. The styrene 'spare' head glues to this stuff just fine. That means you can use sprues from other models and parts from other models readily.

There is a tiny wedge of plastic with the legs in this picture. I cut that from the waist of one of the figures. This wedge will become the spacer to hold the legs properly spread for 'pilot' work. Gotta be able to push the rudder pedals.

Now the wedge is glued in place and the bodies are ready to be joined! Lots of glue, lots of patience and some sawdust. Let the surfaces get rubbery and it is easy to shape the thing the way you want it. I manipulated this one for quite a while before I got him sitting just right. That also required filler at the back since I had a gap after adjusting the back angle.

And here he is, waiting for arms. You can see the sawdust filler. I'll put more glue on the dust and press it flat, let it dry and then shape him for painting. It turns out he won't fit in the Piper J3 model, I can't get him through the door. So he won't be finished until the Boeing 40 plane is ready for a pilot. That's an open cockpit plane so he will go in fine.
