Broadly speaking, the human-manufactured part of civilization is 1/3 metal, 1/3 plastic, and 1/3 ceramic.
Replacing the plastic part with 3D printing on the home scale provides significant environmental advantages and cost savings in civilization. The environmental advantage comes primarily from the reuse of plastics - instead of throwaway plastic, all thermoplastic can be recycled by remelting and spinning into 3D Printing filament. The intent of OSE is to develop a robust capacity for plastics recycling on the home scale. This means grinding, melting, and extruding plastic - to produce 3D printed filament as well as plastic-fiber composites for plastic lumber. The cost advantage comes from free feedstocks from the local waste stream - where the production of 3D printed objects then only costs the energy of recycling and 3D printing.
As such, OSE puts a specific focus on 3D printing for any plastic parts that can be substituted - compared to buying these parts off the shelf. This includes greenhouse glazing, plumbing, tubing and hoses, seals and o-rings, drive belts, tires and tracks, electrical, and other useful parts - whenever possible. The goal is import substitution to locally-produced parts.
It is estimated that a high-performing 3D printer could print about $4k of otherwise purchased materials for the 2016 version of the Seed Eco-Home - at a cost of about 1/10th of the off-shelf value.
3DP substitution is a separate item in the Development Template- where a team of OSE Developers can tackle this task as a separate, important item - in parallel with the rest of the development process.