Advice regarding one off prototypes

I am looking for some advice regarding what I suppose is really a sculpture. I need a large clenched style fist created at approx 30" tall.

At first I was going to purchase Gnomon’s tutorials on sculpture. But then I realised that buying lots of clay, dvd’s and attempting this could simply be a disaster! Then I thought of prototype style companies that could possibly make a plastic version of what I need?

I have ‘some’ experience of 3d modeling (Maya) and could create a 3d model of what I need. Could this then be sent to a prototype company to mold this in plastic or similar? Would this cost a lot to produce? I admit I know very little in this area of design but I can only say I enjoy learning and I am intrigued to find out my options.

Any advice or suggestions would be greatly appreciated. Thank you!

The term “one off” is subjective to the industry. Do you mean you only need 1 prototype part & that is it? If you only need 1, your best bet would be a subtractive process like a CNC machined prototype.

If you need for instance 20+ prototypes then you would be better off going with an injection molded prototype.

→ However for a large clenched fist "30 tall, you will need to consider the interior being cored out to a uniform wall thickness to avoid process issues for a injection molded prototype. Other design considerations such as parting line and draft will need to be addressed if you decide to use injection molding process to create your prototype.

We provide both subtractive CNC prototypes as well as injection molded prototypes.

Most suppliers would require your 3D model in the method they are most comfortable with, so it is hard to say what they would want. We use step & iges files mainly.

Hope this info helped. Good luck on your project.

Thanks for the advice. Yes I only need one. It’s really a sculpture I am looking to create as appose to a prototype I suppose. The sculpture would then be painted as part of an art show. The sculpture would originally be created in a 3d package such as maya/zbrush.

I am looking into 3d printing at the moment which seems to be what I am looking for. But looking through uk based companies ‘example’ costs seem ridiculously expensive. They require a 3d model before giving a proper quote. However due to the time needed to create the 3d model I want to know if it is a viable project cost wise before taking the time to create a 3d model.

One thing I did find was fab@home fabber machines. Has anyone any experience of these? There seems to be community of people who use them, but as yet I have yet to see the max dimensions of anything produced. Would this type of machine print good enough detail for such a sculpture? Lines in the hands and finger nails etc?

The other option would be to use a company in china. Reading through forums there seems to be a massive difference in price. Anyone any experience of 3d printing or fabber machines?

For a quick quote from a 3d printer, send a model of a hollow ball on a hollow cylinder to the correct scale. It should take you about 30 seconds to model it, it is close enoough to the shape of the fist because the model shop will quote based on the overall size, not the details of the model. That should give you a good ballpark figure.

My guess is that it will be a very big ballpark. You could consider doing a fiberglass mold. The fiberglass is typically laid up onto a foam plug that would be the shape of the fist. Carving foam is something you can do yourself at a cheap cost.

Cheap/fast/quality - pick 2.

Talk to a foam carver in your area. You can get a pretty decent finish quality (as long as its not brushed metal…)

Nurb is right, finding a sculture/modelmaker would be the best answer, as they can help you figure out what your after.
Any machining involved is going to be pricey, unless that’s not a problem. The project you are explaining would most likely be a sculpture enlargement service, usually a small scale model is scanned and enlarged through a milling process.

Check out Direct Dimensions
You could have them just scan a fist. I worked with guys from the toy industry that said a lot of today’s realistic collectible toys are made from scanned people that they dress up in costumes. The sculptors just do the finish work like fabric drapes and such. You got the right idea ask around see what you come up with. Goodluck!

Hi Matt,

Although rapid prototyping will give you an accurate representation of your model, I think the size (or the knock on effect on cost) will be your sticking point. Do you mean 30 inches (762mm)?

You mentioned you’ve been looking at UK companies, is this where you’re based?

What does your surface finish need to be?

Conventional Rapid prototyping processes won’t be much use on a piece that large. I think the cheapest way of actually getting your object would be finding a place that can CNC mill a large piece of foam. That will give you the cheapest base material cost which is very easy to machine, which will lower the cost of your machining time. Your surface quality will be rough, which will put the majority of the burden of finishing on you, but if price is your priority this is fairly straightforward, albiet labor intensive.

If you get your giant foam model, you can then fill and sand the surface the good old fashioned way (lots of bondo!) and paint it yourself. Since even if you were to go with a rapid prototype it will give you a rough surface, this is inevitable anyways.

If you had a larger budget I would say you can go with a much denser material like Renshape but I think that will still put your price very very high.

I agree with Nurb…

If you have any sort of film industry near you there are probably more than a few capable foam carvers that might even be able to work from an orthographic sketch - saving you the trouble of creating a 3d model.

My local supplier for this stuff is:

Matt you might want to contact my friend RL Blair. He simply goes by RL. I know his name, but if I told you, he’d kill me.

RL has been a “one off” sculptor for years. A lot of his work is spread around the planet at various Disney theme parks. He seldom works from dimensioned drawing. The Imagineering crew at Disney usually provides roughly dimension sketches … cartoons actually. RL’s range is quite wide; Disney characters, birds, wildlife, the human form.

Go to:

You can probably do this yourself, which would definitely be cheaper than any of the other alternatives. If you can find some 4 lb density (or heavier) urethane foam, that would be the easiest material to deal with. Urethane carves better than EPS (expanded polystyrene, aka Styrofoam) and it isn’t nearly as susceptible to melting when coated or painted with solvent-containing materials. There are lots of coatings that work pretty well for this stuff, that will harden the surface. You can fiberglass over it too. Handsaws and rasps will remove the foam quickly - the dust is fairly nasty, but if you wear a dust mask it won’t kill you right away. Don’t use a hot wire to cut this type of foam, though - the fumes it makes when burned are quite toxic, and might do what the dust won’t. Here’s one company that makes it: - but if you can find a supplier near you, it will save some money on shipping (look for “rigid urethane foam blocks”).

Of course, if you’ve got more money than time or skill for this job, let me know - we could scan a fist for you and produce it in foam with our 4-axis CNC mill ]

Right on!

Andrew Werby

SLA could be done in 1 shot, but very expensive for something that size. Maybe find a local CNC shop that can cut foam? That is how the large sets and characters are made for Disney.

Matt, the RepRap/Maker Bot machines use same basic technology as the Stratsys… that is they extrude a plastic through a tiny nozzle. Something that large would take way too long not to mention those DYI machines have small build platforms too small for a part that size. Not that you couldn’t built it in pieces, but the more pieces you put together the more the accuracy diminishes.