DIY' (3 letters) Do-it-yourself purchase is a term used to describe a purchase of a product that requires assembly or installation by the buyer. The two crossword solutions for this term are 'KIT' and 'DIY', both of which are three letters long. 'KIT' stands for 'Keep It Together' and is used to describe a set of parts that need to be assembled by the buyer. 'DIY' stands for 'Do It Yourself' and is used to describe a product that requires the buyer to install or assemble it.