Quote Originally Posted by CoRDS View Post
this may be a dumb question but what about the 30cm ones and just cutting/grinding them down to 27cm with a cheapo tool from bunnings
this, and a bit of paint to touch up the ends if you get white ones.

or get a 25cm one and live with the bit of overhang. you'll be fine as long as you don't put more than half of the weight above the overhanging part of the shelf. Which will be extremely hard to achieve.