A prototype—a conceptual model of an idea for a new product—can be made from virtually any material via numerous tools, materials and processes. In product development, prototyping often entails the latest technological means to produce a result that closely approximates the intended end product.
You don’t need all of the latest gadgets in order to build a solid prototyping workspace; all it takes is wisely choosing the right tools for you. Here are some simple and not-so-simple tools, materials and processes (some of these overlap, such as 3D printers and their process):
It takes up a lot of space, but the handyman’s best friend is a prototyping fixture due to its ability to cut through thick material such as wood. (Many inventors use plywood because it’s so inexpensive.)
With a simple switch of the blade, a table saw can also be used on metals for creating tube frames or other metal-based prototypes. It will easily zoom through PVC pipe, another commonly used material for proof-of-concept prototypes.
If you want to max out the prototyping potential of your table saw, see if you can outfit it with a kit that turns it into a table router.
Another versatile cutting tool, a laser cutter is good for materials that include paper products, some plastics, wood, rubber and fabric. When designing prototypes for laser cutting, you can draw the shape in CAD software and create tongue-and-groove features; cut pieces out of the desired material; then puzzle them together and lock them into place with super glue or solvent.
With a laser cutter, you can also design pieces that can be lined up and stacked together to make a prototype with more substantial thickness. This technique is commonly used when designing parts with gear trains. Typically, all of the pieces in the stack are given a common set of holes that are cut out in precise locations with the laser, and long screws or bolts are used to clamp them together. Once clamped together, they can then be sanded or filed down to make curved shapes for grips or other features.
Water jet cutter
This is used for heavy-duty cutting of flat parts in metals or thick plastics. It can also cut wood, composites and foam. A laser jet can only cut through one-fourth-inch thick plastic; the water jet can cut through up to 12-inch-thick steel. This is great for making prototypes that need metals either for strength or the ability to withstand heat.
The same tongue-and-groove design techniques used with a laser cutter can be used to make metal parts, and can be brazed or welded together to make strong parts with 3D geometry without having to machine them out of solid billet. The water jet can also be used to cut wood into precise shapes without having to use a saw.
Another essential prototyping element, the rotary tool with its varied bits and attachments can be used to grind, drill, sand, cut, saw, and polish. Many rotary tools even have accessories that can turn them into a table saw, router or drill press.
Make sure you get one with variable speed and an assortment of bits so you can work on different types of materials. The cherry on top: You can get a solid rotary tool in the $100 range.
If you’ve got to have a metal prototype, you’ve probably got to have one of these in order to accommodate the material’s more rigid properties. A shear/brake can quickly cut and bend metals, and switching between the two is just a matter of where you place the piece of metal.
All you need to do is pull the lever to affect the part. Though the thickness of the material you can use depends on the size of the break, it is usually possible to bend short sections of up to 1/8” thick steel or aluminum for most desktop-sized units.
It’s recommended to install this equipment on a heavy-duty shop table, due to the heavy loads. An office desk may not hold up.
Hot glue gun
This is an underrated all-purpose fastener that is fast (once the gun is warmed up) and can be used on nearly every kind of material, including metal. A hot glue gun is also great for prototypes that have electronics or wiring; little dabs of glue can hold wires in place as a stress reliever, or small prototype circuit boards can be completely potted in hot glue to keep stray pieces of metal from shorting them out. Plus, if you glue two parts together and decide to rearrange them, the parts can usually be used again once the glue has been scraped off.
The guns come in many different sizes and power levels. Although regular craft glue guns are fine for most applications, commercial-grade hot melt guns heat up fast and flow better than consumer models.
Mini CNC router
Available from many different manufacturers, a mini CNC router allows you to cut perfect shapes. Many of them use small rotary tools, such as Dremels, as the cutting heads, which gives you even more value for that investment. These are in the $1,000 range to get a system up and running.
Also known as additive manufacturing, 3D printing is an essential tool for professional prototypers—and the technology is becoming less expensive for consumer-level models, with some quality products in the $500 range. (They are even less in a kit version but require a few hours of assembly, and they require some software tuning to get good, consistent prints.) 3D printers can generate parts with complex surfaces in just a few hours.
The SLA 3D printer is one of the top-of-the-line prototyping devices. SLA is a resin-based type of 3D printing that uses ultraviolet light to cure the resin into the desired shape. It makes parts by tracing the geometry of each layer with concentrated UV light produced by a laser. The build platform is lowered into the resin bath after each layer to make fresh resin available for the next.
Depending on the geometry of the part, a wiper blade skims the resin every couple of layers to keep it building smoothly. The software calculates where the overhangs are and it prints a spider web like matrix of support structure to keep the part stable. Once the build is finished, the parts are scraped off of the build platform, and the supports are torn off by hand. Then the parts are scrubbed and rinsed in an alcohol bath to remove the excess resin. The finished parts are dried off and set into a UV light box for about half an hour to cure to their finally toughness.
You don’t have to break the bank or use exotic materials to make a good prototype. Paper and paper-formed products such as card stock and cardboard are commonly used, even if they rarely have the material properties of a finished prototype.
Card stock is useful because it is relatively sturdy and thin, making it easy to work with. Cardboard cut from shipping boxes has good strength.
You can use CAD software to lay out flat-pattern shapes that can be printed on card stock and folded into 3D shapes.
Another flat prototyping material that is similar to paper products and available in retail stores, foam core comes in many different thicknesses and can be carved into 3D shapes. If you need to come up with form models or ergonomic studies for products but 3D printing is too expensive for you, foam core is a great alternative.
Hard insulation foam
A great way to make prototypes quickly and cheaply is to use hard insulation foam, typically pink or blue and found at most home improvement stores. It is inexpensive, comes in large sheets, is easy to cut and can be glued into nearly any shape. It can be penetrated easily, and toothpicks can be used to pin pieces in place before gluing.
Hard insulation foam can also be cut into different profiles that can be glued together to create complex surfaces. It can even be used as a substrate for fiberglass molds.
Besides its use for prototype innovations that involve some kind of liquid handling, PVC pipe can also be used structurally. PVC tubing and fittings can be glued together to form simple frames or can be used as linkages or other mechanical components.
PVC tubing comes in such a wide range of sizes that it is suitable for many prototyping applications. The cylindrical shape can also be used as a form to bend thin pieces of sheet metal or tin foil to create perfectly curved shapes.
Among the most functional plastics for prototyping:
Polyethylene terephthalate (PET), of which many beverage bottles are made, is rampantly available. Soda bottles are tough and are great for prototypes, especially if there is fluid handling component to the innovation. High-density Polyethylene (HDPE), another plastic commonly used for bottling, is useful as a prototype material for handling corrosive fluids. It can also be used as a sliding surface between parts, and tubes of it can be easily cut to make bearings.
Vinyl and PVC are a very versatile family of plastics. Vinyl can be made rigid or flexible depending on the formulation, which makes its applications wide ranging. The inexpensive and widely available PVC is one of the best prototyping materials. PVC pipe and fittings can be used as a modular building system, and it is easily locked into place with PVC cement. PVC cutters make it easy and clean to cut—though PVC should never be burned or laser cut. It will release toxic chlorine gas.
Styrene is a great prototyping material. Sheets of it are inexpensive, and up to about .060″ thick can be cut with regular scissors. It can be bonded easily with super glue or model cement, and it holds paint well. Thin sheets of polycarbonate (PC) can be cut with scissors and bonded together with super glue. PC bottles can be cut with a Dremel tool or saw and can even be threaded to accept pipe fittings.
Broken product parts
Many consumer products are filled with great mechanical components such as gears, axles, springs and buttons. Keep broken parts from items such as a vacuum cleaner or blender to use as spare parts for future products. Toys are another great source of mechanical components; it can be much cheaper to harvest a motor or gear train from a toy than to buy one.
For prototypes using circuits, you can scavenge from VCRs, old gaming systems and electronic toys to harvest low-level components such as resistors and capacitors, or even higher-end components such as speakers, motors and accelerometers.
This is one of the most popular ways to turn a block of raw metal into a finished part for a prototype. Machining is any process that uses a tool or bit to progressively remove small amounts of material to “whittle” the material to a finished dimension. The two most popular methods are milling and turning.
Milling, done on a milling machine, uses a rotating cutting tool to cut a block of material that is fixed to a moving bed. Turning is done on a lathe and has the opposite setup where the raw material is the spinning part, and the tool is slowly moved against it to remove the material.
Welding allows separate pieces of metal to be rigidly attached to each other. There are many different styles of welding and welding machines, but the most common are electric arc welders. They work by using electricity to melt the area around the two adjoining pieces while a filler rod of metal is fed into area to join them. Once the pieces are cooled, they are very strongly bonded together.
One of the biggest caveats to welding is that the materials being welded together need to be of similar metals and similar thickness. The process dumps a lot of heat into the parts, and when they cool they can warp. Parts for prototypes that need accurate features need to be machined after welding to get the required accuracy.
A way to create highly detailed, yet thin metal parts, photo etching is a similar process to making photographic prints in a darkroom. A photosensitive laminate is placed over a thin sheet of metal. Then a mask is placed over the laminate and the sheet is exposed to UV light. The sheet is then put in a developer bath and the exposed areas are dissolved, leaving laminate to protect the metal in certain areas. Then it is placed in an acid bath and the unprotected areas of metal are dissolved away leaving the finished part behind.
Photo etching is only possible when working with metals up to .080” thick, but it can be done on just about any type of metal. It does not require special tooling, so iterations of prototype designs can be made cheaply. One of the most common uses for photo etching is to make copper traces for circuit boards and other small parts for electronics.
Blister packaging is one of the most common uses of vacuum forming. A piece of stock material is heated and stretched over a mold shape to make a part. In contrast, most consumer goods are made by injection molding, in which liquid material is forced into a mold cavity and left to freeze into shape.
In a vacuum former, a piece of stock plastic is locked down above the mold form and a vacuum chamber. A heater is brought in close proximity above the piece of plastic and allowed to warm the plastic to a prescribed temperature. When the material is at temperature, the mold form is lifted up and brought in contact with the hot plastic. At the same time, a vacuum pump is activated in the mold chamber and causes the hot plastic to stretch and wrap around the mold form to make the desired shape. Once the plastic cools, the part is removed from mold and it stays frozen in place.
Always wear protective eyewear and keep a first aid kit nearby. Also keep a small eyewash bottle around, as well as a small fire extinguisher. Work slowly and keep all safety devices on your equipment in place and functioning. No licensing deal is worth losing a body part or destroying your garage or house.