>> One Idea that I've come up with, at least for a prototype,
>> is to use vacuum forming plastic.  This method is used by
>> hobbyists all the time to make plastic one of a kind, or
>> even limited production parts.

> Well, I was actually thinking about buying ready-made keycaps,
> since I don't have any experience with forming molten plastic
> nor space for the equipment.  The method does sound interesting,
> though.  After you try it, please let us know whether it worked
> for you or not.  Negative result is still a result.

It works fine.  It's used all the time in plastic modeling.  The
suppliers have pre-cut plastic sheet specifically desgined for it.
Thin (0.010") clear sheet is frequently vacuum formed to make a
better looking aircraft canopy.  Master can be the thick injection
molded plastic canopy shoved full of modeling clay (heat sink).

Fine Scale Modeler magazine, May 2002 issue, has an article on
"Build A Simple Vac-Form Rig".  I haven't read the article yet...
Magazine is available from your local hobby store or mail-order.
Details at http://www.finescalemodeler.com .

Decades ago, Mattel sold a toy vacuum former called Vac-U-Form.
It has a flip-over frame that held ~3" x ~3" sheets of plastic
via holes all around the edges, a heating side to soften it, and
a stage with hand-operated vacuum pump.  Vac-U-Forms are still in
demand on the used market today.
                                                Lee Jones

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