Metal leather creasers can be used for both functional and aesthetic purposes. They generally perform better when heated, as they more smoothly mark and glide into the leather, forming the creases.
Alcohol heating lamps are a common way to heat up these creasing tools while working on leather craft projects. They are usually comprised of a small metal reservoir filled with denatured alcohol, that when lit, provides a steady flame. Usually attached is a metal extension where the creasing tool can rest while it is heating on the flame.
If maintained properly and watched closely during use, alcohol-based heating lamps can be an easy way to heat your creasing tools right by your leather working space.