You can't patent a design. There is a thing called a "design patent", but keep in mind that the word "design" has many definitions and the design patent does not cover the appearance of something.
You can copyright and trademark designs. Owens Corning has a trademark on making insulation pink. There's a company that recently won a very important court case defending a copyright on making ironing boards gold color (these are professional ironing boards used in commercial launderies) This is the first time that a specific use of a color has been copyrighted (not just trademarked). Harley Davidson is currently working with the Patents and Trademark Office on the details of trademarking the distinctive sound of a Harley.
If you design a knife, then you have a copyright on that knife automatically. But, two things are true: first, there are no copyright police who run around and arrest people who violate your copyright. It's up to you to police your own copyright. Second, copyrights are very narrow. The violator has to dupicate your work virtually exactly.
I'm no expert, but unless the two knives are open and I can see the markings on the blades, I can't tell the BM3500 from the SW1500. IMHO, SW has stepped over the line and infringed on BM's copyrights.
But, again, there are no copyright police to pull SW over and ticket them. BM would have to sue them. It would be a messy and expensive court case. BM would win, but they'd probably have to pay so much in legal costs that it wouldn't be worth it. BM apparently feels they'll get a better return on their investment by investing in new designs, on research and development, on hiring new good people and training and retaining their existing quality workforce, and on improving their equipment and facilities.
Chuck
[This message has been edited by Gollnick (edited 23 August 1999).]