The TOIlet website says: "The TOIlet project attempts to create a free
replacement for the FIGlet utility.".
<http://caca.zoy.org/wiki/toilet>

Guix has a package for FIGlet.  Guix does not have a package for TOIlet.

I looked into this and contacted FIGlet with the suggestion to improve
the copyright and licensing information in the comment headers of the
FIGlet source code files.

I have attached the content of the message I sent to FIGlet as it
includes further information.