Let's assume that someday you will have, in your home, a humanoid robot helper. The robot, because it's shaped like you, can use your tools and move easily around your house. It folds the laundry, it helps your elderly mother up the stairs, and on Sundays it makes brunch for the family. It's capable of handling almost any household chore you can throw at it.
Now let's imagine that you're out on the lawn, kicking a ball around with your son. Your robot helper is in another part of the yard, its back to you both, fixing a drainpipe.
The average home builder could go his or her entire life without drawing a line in CAD, but it'd be a shame. Three-dimensional rendering programs like CAD let you, or someone else, visualize what you're about to build with high accuracy. That lets you suss out potential problems, sort out fine details, more easily outsource parts of the build and share your groundbreaking designs with your peers (or your wife). CAD software is also useful if you're producing drawings of extensive projects, or drawings that need to be revised frequently, or drawings on which multiple people are collaborating. Paper and pencil drafting methods, themselves far from easy to master, fall short when projects get bigger - especially absent a team of draftsmen working in your shop. For me, the need to share and collaborate on drawings was the final straw that pushed my drafting into the modern age. And fortunately, there are a lot of inexpensive options for someone just dipping their toe in the CAD waters. Here's a run down of the options I considered and the software I chose.
You can stop pounding on that anvil now; steel fabrication has moved onto the web. Shapeways, a company that made its name offering custom 3-D printing in plastic and resin, will now print your designs in stainless steel. All you have to do is upload your brilliant CAD design (or pick from a range of stock items). Shapeways will print it out in cold, shiny steel, and mail it to you.