I chose to make my very first printer (a Mendel90) from scratch, using nopheads plans but sourcing all the parts myself. I was in no rush to have one so didn't have a need to buy the kit, but you get intimately acquainted with how one works when you do the scratch build. I have learned quite a bit about how they do their magic, all the little idiosyncrasies of different hardware and software, and what tweaks affect the end product (good and bad ones!) I'm at the stage where I I'm printing direct to the glass (PLA prints), no glue/tape/juice/hairspray..or any other menagerie of methods for making prints stick..I simply scrape the glass with a boxcutter blade, maybe wipe the glass with a bit of tissue and isopropyl if I can see it needs it, load the g-code and click 'print'. These are techniques you learn and develop through doing things the hard(er) way vs simply unpack, plug in and click play.

In saying that, I did have some practice by designing and engineering a conversion of an A3 inject printer into a CNC machine..so I wasn't totally in the dark when I built the printer.