Illumination: Gold
The gold in medieval manuscripts was real gold leaf. Putting gold leaf on
paper is a difficult process and not really necessary for amateur purposes.
You can find a good description of how to do it in Donald Jackson's book
"The Story of Writing". There is also fake gold leaf which is
slightly easier to apply. You can use this for practise, and avoid wasting
real gold.
For us who like to avoid unnecessary difficulties and expenses, gold paint
will do.
Much like other paints, gold comes in several varieties. You can get it
in tubes, just like gouache. I can't give you a brand name here, but tube
paint is usually good, and it may shine even more if you burnish it carefully
when it has dried. There are gold crayon pencils, but they don't give enough
metal shine. You might use them to fill in small errors in tight corners.
Water colour "cookies" of gold also give a very pale and boring
colour. You can get "gold bronze" powder from the chemist's and
mix your own paint - just don't sneeze or your room will suddenly look like
the interior of Fort Knox.
Bookbinders sometimes use a paint made with real powdered gold to make repairs
on gold leaf surfaces. A better alternative is ready-made gold ink (intended
for use with a dip nib), which is pretty good, only don't put it in a fountain
pen because it will clog. Applying gold paint with a sharp pointed dip nib
is a good way to get fine details. Gold ink usually comes in ridiculous
little bottles and costs a lot of money. I use a gold paint called Pelikan
Plaka "Rich Gold". This is sold in the same kind of bottles as
the other Pelikan paints.
One problem with all ready-made gold inks and paints is that you can't dilute
them with water. Toward the end of a bottle, it will get thicker and thicker
until you get a muck that you can't use. Throw it away and buy a new bottle.
The "Pilot Super Color" gold and silver felt-tip markers are easy
to use, but the gold is slightly greenish and rather pale. I confess to
having used them occasionally, but I don't know if the paint will last.
And the points aren't thin enough for really fine details.
Finally, remember that it is possible to do beautiful work without gold.
The Book of Kells has no gold at all, just yellow paint.