Well, first time for everything! First, and I just want to get this out of the way, the base images I worked with belong to the Team Fortress Wiki. I take no credit for them.
Now.... I actually can't think of what to call them. I didn't think of any particular style; I'm not sourcing another game or franchise. Oh well. Just to let you know, these were designed for the FrankenHUD; I have not tested them on the default setup, but I assume they work just fine. If not, let me know- and I'll see what I can do.
EDIT: New in-game shots are up; sorry about that.
EDIT 2: Updated the Blu Engineer's Helmet and gloves. Not perfect, but better. That should, SHOULD be the last of the coloring mistakes (I hope...)
EDIT 3: This should be the last of the edits. Just made a proper Spy Outline to go with the rest. That's it.