Nanomanufacturing techniques can usually be categorized into one of two groups: top down and bottom up.
Top down techniques, including lithography, usually involves a bulk material (larger than 10 nm) that is altered in some way to form the desired product. These methods often but not always involve removing material from the bulk material and thus, leave a considerable amount of wastage. However, this group of techniques still continues to be reliable and is commonly used since they are typically older and more developed than the bottom up ones.
If the top down techniques are comparable to carving an owl out of a wooden block, then the bottom up techniques are likewise comparable to building an owl out of wooden chips. These techniques, including self assembly, are often yield less wastage since they required the building up of pieces. Nonetheless, this is not always the case as sometimes, a component used to build a nanostructure requires a co-component that is not present in the final nanostructure. This type of techniques is becoming increasingly more common and is advocated by many scientists for the building of nanobots.
References
http://www.nature.com.proxy.hsclib.sunysb.edu/nature/journal/v437/n7059/fig_tab/nature04166_F1.html
