This is the most important area for you to spend your time and money!!!
A patent is typically the first place where a new inventor decides to
spent his money. For upwards of $3000-6000, you are betting on some
high stakes, when less than 5% of all U.S. patents which issue develop
into products which eventually become sold! Also, prototyping your
invention first often leads to improvements you may have wished you'd
included in the claims of your patent. Remember, you do not need a
patent to negotiate a contract for royalties on an invention.
Don't be afraid to make your first prototype! Think of a prototype
as a scaffold on which you stand to see how to construct your next model.
Prototype the difficult, trickier part of the invention first! So
much of the rest of your prototype (even patent claims) are determined
by how this works out.
Prototyping: Things to determine
- What is the purpose of your prototype?
- A "rough draft" to see how to make a better one.
- A study of how to solve the more difficult features.
- To play test.
- To make a demonstration video. (The action can be
simulated so that the prototype doesn't have to
- To show to a toy or game company.
- To solve manufacturing problems.
- What scale should you make your prototype?
- Actual scale.
- Larger scale: e.g., it may make it easier to make and prove the smaller mechanisms.
- Smaller scale: e.g., if it would take too much space to demonstrate a full-size model.
- How will your prototype be built? (the following topics are discussed later on this page)
- Paper or cardboard.
- Machine shop.
- Model making.
- Electronic Breadboarding.
- Sewing of Fabric.
- Plastic Molding.
- What materials can be used on your prototype?
- Wood. Pine, balsa wood, hardwoods.
- Aluminum, Steel, Brass, Copper. Tubing, strips, sheets
and extruded shapes can be obtained at hobby shops.
- Polystyrene plastic. You should keep sheets of this
in thicknesses of 1/64, 1/32, 1/16, 1/8, and 1/4" -- check
a plastic supply company. Tubing, strips, sheets and
extruded shapes can be obtained at hobby shops.
- Acrylic plastic sheet. Adhesives are availble to
fashion structures from this. Useful when transparancy is
Prototyping: Sources of Components
- Buy toys, take them apart, and build your prototypes from them.
- Low cost components from: 99-cent stores, hobby and craft stores
- Teacher Supply Stores -- they'll give you a 1-in thick catalog with photos
and descriptions of all they sell which you can keep on hand to look through.
- You can get all sorts of compontents, material, and gadgets from American
Science and Surplus, 847-982-0874. Get their catalog and visit their
- Same thing for Edmund Scientific Co., 609-573-6250, though not at surplus prices.
Get their catalog and visit their
- Look for an electronics parts source in your town and visit
there. Something more obscure than a Radio Shack. You're likely
to find hard to find mechanical components there, too.
Prototyping: Using Adhesives.
Adhesives provide one of the most useful means of fastening
items when you are prototyping. The choice of adhesive will
be determined by the type of material you are joining.
- Cyanoacrylate (super glue)
- A quick drying brittle adhesive joins almost anything
with a little quantity.
- Will not join polyproylene.
- It is worth using an accelerator with cyanoacrylate.
An acceletator (one trade name is "Zip-Kicker") is
sprayed onto the adhesive from a pump bottle and will
instantly freeze it. Get cyanoacrylate and its accelerator
at hobby stores.
Also sprinkling baking soda onto the wet adhesive fills
it in and causes it to set up. You can build up areas
this way. Try it!
- Methyl Chloride
- This is a solvent which joins some plastics together.
Use it on ABS and especially polystyrene. Get it at
- Hot-Melt Glue
- If you don't have a hot-melt glue gun, get one. This
is a very convenient method of joining things. It bonds
somewhat to polypropylene. It is great for strengthening
and supporting joints you have already made with cyanoacrylate.
You can get the glue sticks in different colors
and can squirt the hot glue (really a plastic) into molds.
Get it at discount, craft, and hadware stores.
- Shoe GoopTM
If all else fails, this product is extremely versatile. I
use it especially if I need to bond cloth to something else.
It will also bond to difficult polypropylene. Find it at
discount and hardware stores.
Prototyping by Using a Machine shop
- This requires mechanical drawings to describe how a
machinist must cut the parts from metal, wood, or plastic
on a mill or lathe. These drawings explain the geometry of
the part with shape and dimensions.
Prototyping by Model Making
- This is the means of prototyping primarily described
in this body of information. Try to utilize this method instead
of using a machine shop if possible.
- I had been creating mechanical drawings for many prototypes
which were unnecessary. Model making is "build as you go"
whereas machining requires that you commit to your dimensions on
everything before making anything.
- Required to control lights, sounds, motors, sensors,
information, etc. A breadboard is a prototype electronic circuit
laid out by descrete components. It is acceptable to solve
these issues outside the prototype and allow wires to enter the
interior for the electronic features. It is understood that all
electronics will be hidden in the final product. Also, there
are chips which can be programmed to do what you want.
Sewing a Prototype of Fabric
- Do it yourself or hire a seamstress.
Molding a Prototype in Plastic
- There are a great variety of materials which can
be used for the mold and used for the molded prototype.
- An original can be sculpted out of wax. Or the original
can be fashioned by cutting up sections of other products,
gluing them together, and filling seams with clay or wax.
The molded prototype will be a one-piece solid.
- Artists make their bronze castings using the "lost wax"
process. Visit an art supply store or school art department t
o learn how this works.
- Materials for the mold: Silicone and Latex mold compounds,
SculpeyTM, Flexwax 120, Plaster of Paris.
- Materials for the molded part: Acrylic casting compound,
various latex and urethane compounds. These materials can be
selected to affect the hardness and flexibility of your prototype.
Prototyping: Focus on Model Making
- General operations
- Cut plastic or metal tubing with a tubing cutter--an
adjustable clamping device with two sharp wheels.
- Use rubber bands instead of springs wherever possible.
Springs are more difficult to adjust.
- Working with Paper & Cardboard
- Many times you can make elements of your invention
prototype from paper or cardboard. Pins through the pieces
can act as axles or pivot points to see how parts will move
together. String can be fastened between pieces to act as
- To cut: scissors, Exacto-knife.
- To join: tape, glue, staple.
- Working with polystyrene
- To cut: score with a razor blade or Exacto-knife, bend it
on the score and it will snap apart. Thicker sheets may need to
be cut with a hobby saw.
- To join: methlyl chloride is fast & easy. Also, cyanoacrylate
and hot-melt glue. Hot melt may warp or melt the plastic.
- Many toys are made from the styrene family, a relatively brittle
and easy to mold compound. You will find parts of toys which are
made of this which will respond to the solvent methyl chloride.
- You can get more information on working with this material from
the manufacturers, two of which are Evergreen Models
(the have a small guide for sale) and Plastruct.
- Working with brass and copper
- To cut: tin snips and tubing cutters.
- To join: silver soldering, fastening with screws and nuts.
- Working with polypropylene
- This material is used in many toys because it is quite
inexpensive, flexible (durable), easy to injection and blow mold,
and easy to color.
It is used to make Frisbees and wiffle balls. It is very difficult
to glue or adhere to.
- To cut: Razor blade, utilty knife, or hobby saw.
- To join:
- Shoe Goop is a good adhesive.
- You might "sandwich" a wall between two sheets of
polystyrene; punch holes in the wall and fill them with
circles of the same thickness of p-styrene, and bond a
surface of p-styrene to each side of these fillers.
- I have joined brass to polypropylene using metal
craft decorative buttons. These have four sharp tines
extending from a disk. Cut tiny slots in both pieces in
the pattern of the tines, push the tines through both
pieces and bend the tines over.
- Or simply use sewing eyelets which crimp in holes
to fasten two materials.
Here is some additional prototyping advice from Bob Hudson, an inventor I've come to know over
the years --Thanks for the great input, Bob!
Hope these are helpful suggestions.
- As for inventors doing prototype model making, I have found that PVC
pipe comes in quite handy; it's readily available at home improvement
stores, it's easy to cut, drill, glue with super glue or PVC glue,
can be heat-formed and it's cheap. It comes in several diameters and
uses easy-to-assemble fittings which are glued on.
- Another material which is readily available is auto body filler
(Bondo). It sets up quickly and is rather easy to form into complex
shapes, it sticks to itself, so it can be built up in layers and it
is compatable with fiberglas resin with which can be mixed to thin it
out if desired. It sticks well to metal and wood which can be used
as armatures for models. It can also be used over some plastic foams,
but will eat into others, so test it first.
- Readily available plastic foams are floral foam which comes in blocks
and construction insulating foam which comes in sheets. There are
also pressurized cans of insulating foam which harden quickly and may
be cut and formed with a knife. While not for the final finish, all
the foams can be cut with a knife and are easily formed into basic
underlying shapes such a doll bodies or teddy bears which will be
covered with some other material.
- Brass and copper tubing can be joined with regular, low-temp solder
quite well; we prefer electrical solder since the flux is non-
corrosive. Silver solder can be used for joints that require
exceptional strength; however, for telescoping and joining one tube
within another we rarely use anything but super glue.
- A good source of toys to be used for prototyping is second-hand
stores (Salvation Army, etc.).
They may have toys that are not currently on the market and may be
just what one needs for a project (if nothing else they will be
cheaper). We recently built a complete prototype this way; 100% of
it was recycled and it was a combination of two popular toys. Maybe
the best is yet to happen; it was grabbed up by the first company we
showed it to (which makes one of those products AND is looking for a
product to expand that line), so now we just have to see if a
- Stereolithography is one of several means of creating a "rapid prototype". It uses 3-D CAD
information to create an "instant" model by printing it (solidifying plastic resin with a laser
dancing on the surface of the liquid) layer by layer.
HERE is an article of how Mattel
has used this method to speed up their design process!
© 1996-98, Ayers Concepts. Last update: 02-19-98.