Looking over the replies to this post, its pretty obvious that some of you have never really actually built anything requiring any amount of measurement.

"Why don't I just give my boss a 33mm piece?" -- and leave a 1mm gap in your house, where ants can come in, and heat goes out....

"Why would I ever need a board 1/3rd of a meter long?" -- sigh it could just as easily be a board 10/3 meters long, or 200/3 meters long. Because 3 is a small prime, and by the fundamental theorem of arithmetic, 3 is going to be a factor in a lot of integral lengths.

Say you are designing a switch with two buttons on it, "on" and "off". Well, the centers of those two buttons are going to be located at 1/3rd and 2/3rds of the length of the plate they are mounted on.

Say you design a crock pot with 3 buttons for the heat, "low", "medium", and "high". You don't want two of those buttons to be 1cm apart and the other 2cms apart!

If you look at countries like, say, Japan, or Germany, which really do use the metric system, you'll find that they measure things not in centimeters, but in millimeters. And the lengths they use are numbers like 48, or 120, which have lots of factors of 2 and 3 in them. Because you divide lengths into 2 or 3 parts all the time.

Which is to say, if you want to actually use the metric system in industrial design, you don't use a lot of lengths which are powers of 10. You use lengths which are divisible by 12 anyways.

There's a reason the U.S. never went off the English system, and why countries like Canada and the U.K., which actually make real efforts to try to go off of the English system still use a lot of English units in everyday measurements. And it's not just because of conservatism, or NIH syndrome.