ID:293361
 
Noob question, but are these freely distributed, and if so, where might I foind them? If not, are we to create them ourselves?
.dmi files are just like any other graphical file, so you can either create some on your own, ask others to create them for you, or try to find places to download some pre-made ones (if the copyright allows you to!).
There are some freely distirbuted collections of .dmi icons on BYOND that you can use, but generally the most common thing is to make the icon yourself in Dream Maker, or to paste images from another source into the icon editor. You can also import several kinds of image files in the icon editor.

Lummox JR