Yeah true unfortunately, (altho i have found a few useful pieces which have come in handy for work related stuff on there)
My own cad drawing skills are still at basic geometry stages so a learning curve ahead for me. I do find the process fascinating tho as i grew up with traditional modelmaking both in hobby and later in professional fields, especially in recent years with the emergence of accessibly priced high quality resin type printers
Iv found 'secret projects' type drawing files avaliable online for 3d printing a bit hit or miss so far (the latter no doubt due to lack of information obtained by the artist) if anyone comes across any of possible interes or indeed has drawn up similar please feel free to share
Sadly the general standard of freely available 3d objects is terrible, not a complete waste of time but right up with that. Meshmixer (http://www.meshmixer.com/) is a handy little tool for combining different 3d models which might make it easier to kitbash your models.