So I would like to create additional options for custom shapes when editing a polygon feature. Something to the same functionality of the 'Construction Tools' as pictured below, but with a greater variety of shapes (like a triangle, pentagon, irregular shape as below, etc).

Wondering what the best method would be to go about this? I'm assuming it's not possible to add custom shapes directly into the already existing Construction Tools panel (tho I'm not technically versed enough to know).. but in that case would writing an Add-In be the best way? Is it possible?
..I probably won't be doing this by myself unless it requires minimal coding experience, but I'd really appreciate if someone can point me to the correct basic approach!