Meter goop -- black or red stationery store sealing was stick and a match --

[Mike Langner]

Or go into any really good stationery store -- particularly one that sells
fountain pens and the like.

Sealing wax generally comes in cubes about 3/4 of an inch square by about 2
1/2 inches long.  It melts at a much higher temperature than either
(cooking/canning) paraffin wax or the venerable Crayola. Melt the end of it
with a match or a heat gun.  Heat guns can be a problem as they tend to blow
the drops away from falling in a straight line downward.

Sealing wax usually comes in red and black.  Red is the most common.

One stick will last you about 500 years.  If the one used to seal the Magna
Charta were still around, it'd probably still have some life left in it !!