Milliput is one of the world's leading producers of epoxy putties. It is adhesive to most materials, tough and durable, and self hardening. Milliput can be used for repairs on many types of materials including metals, plastics, masonry, wood, glass and ceramics and can be used in places where welding is impractical. Milliput products are available from most leading model/hobby shops, art and craft suppliers, independent hardware stores and plumbers merchants.

Some modelmakers and propmakers sculpt with it.

The simplest tasks are often the biggest challenge. Many can program a microcontroller; not as many know how to make a simple actuated joint, a custom gearwheel, or a custom chassis for their creations. With 3D printers, we've been promised a revolution in desktop manufacturing, but many of the issues are more fundamental - having to do with mastering CAD software or understanding materials science to make lightweight and durable parts. Meanwhile, on the manufacturing side, a simple, affordable, and home-workshop-friendly solution - CNC machining coupled with resin casting - is already within reach.

This guide is more or less modular. If you're interested in buying a CNC mill, keep reading. If you already have one and know how it works, or want to try the overall process with a 3D printer or other manufacturing process, you can skip directly to the relevant part.

lcamfuf wrote a book on some classic DIY/maker techniques for building stuff, such as CNC machining, mold making, and resin casting. Cost is a consideration in everything he wrote about so if you're not rich or well connected but want to get into building things, give this a read. You can read it chapter by chapter or all in one go.