from Real Clothes Volume II
(c)Perestroika Designs Ltd.

Help! Ken's perfect dress shirt suddenly looks like a parody - the buttons are so out of scale! No wonder - the dolls are approximately 1:6 scale, and even doll buttons - when you can find them -are often 1/8" thick. That's like your shirt button suddenly being 3/4" thick.

Not good. So the Perestroika elves put on their restructuring caps, and came up with some tips for improving the situation. 

You'll need: a vise, a jeweler's saw with lots of fine (2/0) blades, a nail file or emery board, some electrical tape, and a bit of practice. With a bit more practice, you'll end up with twice as many buttons as you started with.

The goal is to reduce the thickness of the button by sawing it in half. The trick is to saw straight, and that takes some practice. Most doll buttons are plastic, which will saw very easily; other candidates are small shirt buttons, which may be made of shell, and are much harder - but still possible.
The jeweler's saw is similar to a coping saw or a fret saw; the critical thing is the fine blade. These saws are used vertically, and take a little practice to use. The blades will cut through steel, but will break very easily if they are not inserted properly (they should sing like a violin when properly tight in the saw) or if you twist or turn the saw even a bit as you work. The blades are sold by the dozen - don't stint!
Second only to the saw blades breaking is the frustration of buttons escaping. A small piece of tape (electrical tape seems to work best) wrapped around the button makes it easier to position in the vise, slows down the escape, and makes the button easier to find when it has leapt to the floor.

The button needs to be held firmly in the vise, so it won't wriggle about, but there is a risk of cracking the button if the vise is tightened too much. If the button moves when you start to saw, tighten it just a bit more.

It may take a little practice to hold the saw and your arm at the angle that will give you a button cut in half, rather than in wedges; the key is how you hold your arm. If the angle is slight, you may be able to sort things out later with a file or emery board, but if the cut is really off, stop; the blades will cut the vise!
There will be some plastic residue on the far edge of the button; the plastic melts as it cuts, and the "dust" solidifies ahead of the saw blade. An emery board or nail file will clean this off. Be careful not to file the edge of the button, since most just have a surface color. (Or be creative and add a white edge to your buttons!)

Most buttons are different on each side, so you won't end up with a pair from the original button. You'll have two sets from three or four buttons.

If the button has a significantly dished top, plan the cut so the buttonholes remain intact. If the top is really dished, you may end up with only one useable new button.
Once you've mastered this, you'll find other ways to create the perfect doll buttons.
Almost anything with an appropriate diameter will make a button; here, tips from antlers were sawn to make 1/16" disks. A pin vise with a bit begged from the dentist makes the holes.
Larger buttons can be adapted, too. A sanding or grinding bit in a drill press will quickly remove the perimeter of a button (be careful of your fingers, use pliers to hold the button!). The key to adapting larger buttons is to choose buttons with small and closely-spaced buttonholes.