Nothing wrong in building something for yourself
or giving info to someone if there is no money involved. Who says its against the law to recreate a product for individual use? If I wanted to copy a Ford Taurus, buy all the parts and build it for myself , I would be allowed to. I would be infringing on copyright laws if I took the ideas , recreated them and produced a commercially available product. Or sold somebody elses plans/ideas, outright .