Pinned for Conceptual Reference
Imgur: The most awesome images on the Internet.
Machination - a variety of GIFs showing how things are made. Items range from food (pretzels, macaroni, pancakes) to mechanical products (chains, wire-fencing, glassware).
90 Degrees Uniform Motion Transmitter
blind pegged mortise and tenon joint - Google Search
Scissor Mechanism 1C - SOLIDWORKS,STEP / IGES - 3D CAD model - GrabCAD