by Lummox JR
Utility: Create a set of autojoiner icons from source icons you supply.
IconCutter is a utility which supplements the BYONDscape column Dream Tutor: All Together Now.

This utility is a timesaver for setting up icons for autojoining. It splices the corners of the icons you give it, to create a brand new file with all the possible icons in an autojoin system of your choice. Version 2 now supports more forms of joining. Besides classing 47-state joins, it can handle 16 and 256, along with new forms 161 and 82, and Foomerian joining. Now you can also include multiple states to join in the same icon, so you can have icon states like "forest0" and "grass17" and so on.

Originally this utility required the user to compile it, but now it operates standalone. The source code is however still included.
Thanks for this Lummox JR.
Link to the Dream Tutor article is dead. It's here.
I'm wondering if this would handle an animated icon properly. Any idea if that's been tested?
In response to FKI
It hasn't been tested, but it should be supported just fine. The cut doesn't do anything with the animation frames, so it would leave those intact.