This article is from the Miniatures Painting FAQ, by Brenda Klein email@example.com with numerous contributions by others.
It's an acquired skill. To convert a miniature requires a lot of
imagination, steady hands, patience, and a few out-of-the-ordinary
tools. Costumes have to be obliterated, faces changed, weapons
removed or added or changed. In all honesty, the processes
involved are more numerous than can be addressed in this FAQ.
Therefore, only the most common modifications will be addressed.
Tools: To properly modify a miniature, you're going to need:
files (round, triangular, square, flat), the smaller the better
X-acto knife and several replacement blades
glue, preferably Zap-A-Gap, possibly epoxy
nail scissors or tiny wire cutters
needle-nose pliers, the smaller the better
sandpaper and/or emery boards
a hacksaw, the finest you can get
any new pieces you want to add (weapons, etc.)
% The most common modification is to change one weapon for another.
For purposes of explaination, a fantasy figure will be used, the
change being from sword to battleaxe, assuming the sword had been
molded as one with the hand. First, clip or cut the sword off on
either side of the hand, being very careful not to damage the hand.
The new piece may be one cut from another miniature, or one
acquired from a weapons pack. If it is the latter, you will need
to measure it against the hand and cut out part of the handle to
compensate. The next step is to make holes in either side of the
hand where the handle enters in order to insert the new parts.
An X-acto blade or file may be used. A pin drill would come in
handy about now.
Once the holes are made, a drop of glue is placed in each one, then
the handles are carefully set in place. The glue should show, as
the extra is needed to keep the parts in place. Hold until set,
possibly reinforce with a little tape, a brace, or some sort of
clamping arrangement, and let set. After the glue is thorughly
dry, a file or emery board can be used to clean up the excess,
Avoid using a knife or razor blade, as you're likely to take off
too much glue and the weapon will simply fall off again.
% Another common modification is to make a miniature suitable for
superhero use. The easiest way to do this is to file and sand
the clothing smooth with the rest of the body, then paint on the
costume of your choice.
A note on drilling, thanks to Andrew Reibman (firstname.lastname@example.org)
"A useful tip for figure converters and folks drilling out
spears to replace them with wire. Before drilling (with
either pin vice or dremel tool)
dip the bit in Johnson's tube wax (what the pros in the
machine shop use), dryed-out Simonize car wax (my choice),
or other wax. Even a bar of soap may work.
"Since a buddy of mine who spent his career
in machine shop recommended this, I've cut bit breakage
down by a huge fraction, and starting and drilling are both much
easier. I use to break my .014 bits, used for starter
wholes in tough 15mm jobs, about once every ten holes -
well that's an exaggeration, but I did break a lot of bits...
The wax lubricates the bit, and "keeps the flutes from
filling/jamming", allowing the cutting end of the bit
to do the job more effectively."
Brian Oplinger (email@example.com) says that turpentine,
mineral spirits, and paint thinner also make good bit lubricants.
If things get hot, though... And remember to ventilate.