Scratchbuilding is the process of creating scale models entirely from raw materials, without the use of pre-made kits. This technique allows modelers to craft one-of-a-kind pieces that can’t be found on any store shelf. Scratchbuilding requires a combination of skills including precise measurement, careful cutting, and thoughtful assembly to bring a vision to life in miniature form.
Or it requires a squirrel brain coupled with unlimited enthusiasm. Oh, and 20-30 years to figure out how to solve problems. That’s my experience anyway.
My motto is measure once, cut twice, measure again, and oh nuts toss the part and start over again!
Way above my pay scale,i stick with kits that I can barely build.
While I was woking on a project (still not complete today 
) I thought - all these hours of research and then building those parts… Nobody is going to give a damn about… And then I thought - if I draw this in 3D and 3D print it… Somebody else could get a copy if anybody is interested!
At that point in time (2018) I couldn’t do 3D drawing - so I taught myself how to do it and since then instead of “cutting and glueing” I do 3D drawings and 3D print them. Some of my designs were only printed once - but the majority caught some other modeller’s eye and I could share, that’s a good feling!