A fun way would be this:

Put the negative in the enlarger - expose the image on a new film in your camera without the lens... (The camera is put under the enlarger as if it is a piece of paper..) Having a "modern" one with a decent lightmeter and automatic exposure, you don't even have to mesure the light...

Expose and develop as normal..

(This was also used to make huge enlargements of an image in order to get big grain and to get a pictorialistic image..)