What is a Polyforge?
The short answer is that a polyforge is a 3D printer. The longer answer is that it is a chemical extrusion and treating machine that takes a variety of liquids and pastes, forces them out into a desired shape, and then subjects them to varying degrees of heat and UV radiation to gain a desired product.
Plastics and Polymers
The most common thing fed into polyforges are plastics and other synthetic polymers. With the proper program, a forge running polymers can create almost anything. This comes from the fact that it can run simple bioplastics derived from algeas to make things like water bottles and disposable cutlery and throw away poly-paper plates, to running high density military grade polymers to make weapon components and such.
Glasstic is a common building material and is silicon dioxide suspended in a water rich polymer. Once the object desired has been created by the forge, a blast of high heat burns away the water and suspending polymer, leaving behind a finished piece of glassware. This can be used to create ceramics, including ferroceramic armors, knives, glass goods, and electronic and electrical components that need high insulation values. Glasstic has grades and can have a higher plastic content, producing nigh unshatterable containers, or can have almost no plastic to create basic glass. Glasstic is used in the construction of large buildings, and the sheets used are often grown and treated on sight, as large canisters of liquid glasstic are easier and safer to move than finished materials.
Metal dust can be suspended in a water based polymer just like in glasstic. The plasteel is treated to a similar heating process, both an at the time of laying down laser treatment, followed by a forging process to ensure the strength of the finished piece. Thus a machine can turn a thick slurry of polymers and metal into a finished metal good such as robot parts, armor plating, construction materials, and almost anything else that needs to be made of metal.
Nutripaste is a gluten/carb based plant material that can be given a variety of shapes, textures, and flavors. Because of this versatility, it can be used to make a variety of finished food products. Food polyforges are different from industrial poly forges as they are designed for food service, and rather than mass producing meals, the machines are more commonly used to make snack foods such as snack sticks, chips, and other things with puffy or crunchy textures. The heat forging process is just cooking the finished product. There are also separate mycoprotein handling polyforges that turn fungus sourced protein paste into the facsimile of met products, with nuggets, sticks, sausages, and other 'mystery meat' goods being preferred.
By using cultured stem cells and cartilage, medical forges can weave and knit together new muscle tissue, sheets of skin, entire new organs and even limbs to replace those injured beyond healing or missing. In this manner, cybernetic implants can have their respective organs grown around them, rather than having the existing organ sliced open and grafted into. Without these forms of organ growth and augmentation, there would be vastly fewer cybernetic upgrades available.
The 3rd Industrial Revolution
The advent of the polyforge, and more importantly, the computers and robots operating them, created a revolution in industry. Production and assembly lines are largely a thing of the past, as most non-durable goods are produced locally by industrial polyforges. The typical arcology has enough space inside to house a light industrial sector.