Large area nanograting patterns are useful in many applications but difficult to fabricate. The authors demonstrate a low temperature dimension reduction method, as a cost-effective alternative to high resolution lithography, to define nanogratings as narrow as 8-10 nm. In this process, the slope of prepatterned polymer gratings, with pitch of 200 nm or larger and width of 100 nm or larger, is contrillably changed from the original straight to curved or sloped. Then, shadow metal evaporation is used to coat the sloped polymer profile to define a much narrower opening. This opening is then transferred to underlying material by plasma etching to form sub-10-nm trenches. The width of trenches can be well controlled by both slope of the profile and angle of metal evaporation. Low processing temperature (as low as 55-85 degrees C-depending on polymer) allows this method to be used with a wide variety of materials.