You just helped me realize the real value of the Open Source Ecology project and ones like it. I've always thought they were neat, but when you add up all the cost of the raw materials and "vitamins" (stuff you can't easily fabricate), plus the necessity of a quite well kitted out shop, it's often not necessarily cheaper than buying the equipment used and fixing it up yourself. But the simple designs make all those field repairs way easier. Also understanding every nut and bolt on the system as you build it creates an intuition about the system holistically.

https://www.opensourceecology.org/portfolio/tractor/