Just some ebuilds that may or may not work.

How to add this overlay with layman

After installing layman with emerge layman, add this overlay:

layman -fa didactic-duck

The overlay's ebuilds are now available to emerge.

How to add this overlay manually

Alternatively, add this as a Local Overlay to /etc/portage/repos.conf/.

Create a /etc/portage/repos.conf/didactic-duck.conf file containing:

[didactic-duck]
location = /usr/local/portage/didactic-duck
sync-type = git
sync-uri = https://github.com/lucianposton/didactic-duck.git
priority = 9999

Afterwards, run emerge --sync to sync the overlay. The overlay's ebuilds are now available to emerge.