If you're going to buid to Col. Cooper's definition IIRC its 1 meter or less, 3 kg or less, can make hits on human size target out to 450 meters, has a sling, iron sights and optics.
I'd build it if it were me but like Mike said, it depends on your skills, abilities, drive and determination. I'd go with an 18" barrel, maybe even 16" (works on the Ruger), plastic stock, ghost ring/peep sights, 1-4X scope with long eyerelief, good sling, and a threaded barrel for flash hider/suppressor.