Tilt-shift lenses are used to alter the plane of focus in your images. These lenses are great for shooting projects that simulate a miniature scene, create abstract effects or for architectural photography.
Commercially-made professional tilt-shift adapters are expensive and are priced around the $1,000 to $3,000 range. All the more reason why Joe Murphy has done DIYers a huge favor by putting together this Instructable that teaches photographers how to put together their own tilt-shift lens.
Murphy has documented his procedure for making a 3D-printed tilt-shift lens pretty well, where he used a 3D printer, 3D modeling program, and a caliper in the process.