The art of scratchbuilding is that of building a model or its parts from simpler materials. Any materials may be used. It is in some sense a very advanced kitbash technique. The line between scratchbuild and kitbash is sometimes fuzzy. For example, John Spangler's Steelskin project uses part of a G1 Sideswipe figure as its frame, but consists mostly of custom-built parts. So, the toy was not entirely built from scratch, but the premade parts are so heavily modified that calling it a kitbash does not really do it justice.