Enclosures

Some possibles from my bookmarks list:

Have you considered 3D printing in plastic. I have a friend in a university lab who routinely does this for prototype enclosures.

Jeremy

Depending on your specific requirements a 3D printer could be an option for plastic enclosures. Companies which offer prototyping services often have one.

So now we know what you're _not_ looking for. But we don't know what you _are_ looking for. How is anybody supposed to be able to offer meaningful suggestions based on that?

What actually is the shape you're trying to get? What size? What colour / surface finish? How good does it have to look (e.g.: visible screws, tool marks)? Any requirements about sharp edges / curve radii? What's it allowed to weigh? How tightly does it have to fit the content? What tolerances (i.e. how equal do those 20 units have to be)? What's the budget, both in terms of money and time? What skill level can be expected from the person building it?

I've used lexan in the past for this sort of approach. Solvent weld the "corners", file to debur, paint.

But, it's hard to get anything other than a bunch of "planar surfaces". (well, maybe if you used *thick* plastic and filed/sanded away a *lot* you could get to an arbitrary curved surface)

The fiberlass advantage -- especially over a wooden form -- would let me "sculpt" the outer surface instead of relying on how many flat "facets" I wanted to glue together :-/

Strongly seconded. 3D printer output material tends to be _way_ too brittle to actually expose to customer hands --- and it's usually in the wrong colour or opacity, too.

It's good to _show_ a shape, but sucks at _holding_ that shape.

As a rough reference point, you shouldn't try to hold an LCD's zebra-rubber connectors in place using 3D-printer pieces only. At least those parts of the setup experiencing pull-stress will break almost immediately.

I had already checked ploycase and hammond -- no joy there. I chased the second link you provided and they don't seem to have anything either.

I'm pretty sure I am going to have to roll my own. So, it boils down to figuring out what the limitations of any process I might adopt would be.

Three ideas: sheetmetal work is fairly easy, if you can find a shop with brakes and shears, they can whip up a variety of flat-surfaced boxy things. Spotwelding or POP rivets or PEM nuts are suitable for the fastenings.

Polycarbonate or acrylic sheeting can be heated in an oven to sag into any mold shape (or over any interior shapes), at modest temperatures.

Lots of 'box' items are available for lots of purposes, can you get a file-card box or a lunchbox to suit your purposes? How about an Altoids tin? Hubcap from a '57 Chevy?

I have seen 3D printer cases that I would not give to a customer.

Its great for a sales guy showing off a NEW product, but the strength of the model is still not what I would expect for a real case.

hamilton

Ooooh! That's an idea! Much less work than fiberglass, too! (though I suspect relying on gravity means you need to constrain your "shape" somewhat -- e.g., I imagine there are "minimum sag radii" :> )

The "how big" question is still out there. A non-rectangular shape could also be a pretty big animated head for a carnival float... ;-)

There are some "craft" approaches, like a papier mache shell over a wire armature or a putty build-up over an existing form. Use that as a positive to create a negative mold and then a small production run using cast resin.

Or, talk to the folks at

Apparently, *other* have managed to do so! But, if you need more details...

Klein bottle

Must not reflect any light in the visible specturm

See above

Yes

tight enough to keep the contents from escaping!

racial, ethnic and religious

Somewhere between rocket-scientist and cancer-curer

Does any of this change your potential solution?? :-/ (If I could boil it down to "X = 2 * 3 + 4 / 5" then I wouldn't need to ask for suggestions, would I? :< )

Have you looked at PacTec Enclosures yet? Link:

-mpm

Ah, excellent! Thanks!

Ah, I had forgotten about them! But, no, they don't have anything "stock", either. Everything COTS seems to be "a box" -- with only minor deviations on that "rectangular prism" theme.

I've done fiberglass molds before. If you want 20 or so units I would do a female mold. Modeling clay, foam and Bondo work great for shaping the male plug and fixing any problems.

I use tooling polyester resin. Any cheap resin will work. Most local fiberglass suppliers will have some brand. Do not use styrofoam with polyester resin as it will turn into a lump of goo. Use a pvc foam - there are several makes. Use Bondo or some resin with a filler to coat all the foam and make sure and sand smooth. Coat with car wax or some other release agent. Then start to make your female mold from the male plug. Use lots of resin and a fine weave cloth for the first layer. For the other layers I usually use some fiberglass mat and any scrap cloth I have in the bin. Glass in some small wood blocks for stability in making the real parts.

Let this all cure and then carefully pop the mold off the male plug. You might have to persuade it a little with a rubber mallet. Clean up any imperfections in the mold with Bondo and some sanding. Dremel with a cutoff wheel works great for cutting the edges of the mold. You can scribe drill marks and cut marks in the mold that will show up on the finished part. I have used a BB bonded to the female mold as a drill "center punch".

You can get gelcoat from local suppliers or on the net or you can make a poor man's version using some clear casting resin and some pigment. I have gotten pigment and supplies from TAP Plastic in the past.

For the final part make sure and wax the mold several times. I usually add some form of spray on mold release as the final step. Lay down a nice layer of gelcoat or resin and then use fine weave cloth for the first layer. If needed stiffen the part by using foam and glass on the inside in various locations. For standoffs and screw inserts you can use a small block of foam. I use screw inserts and just fill the threads with a blob of hot glue. Any resin just pops off and the hot glue plug will pull out of the threads. If there is going to be any real stress on the screws you can carve out a pocket in the foam and fill with a milled glass - resin mix. Let it cure for a minute or 2 to thicken and then push the screw insert into the pocket. Biggest problem I had was making sure they stay aligned. What I did for one part was made a wooden jig where I could screw 4 insert onto locater screws and then pressed them into the milled fiber mix. The jig held everything square.

Take a look at

If you want to go the acrylic sheet method browse US Plastics

Have you looked at OKW?

Try

RS Components and Farnell sell some of their enclosures.

Regards Anton Erasmus

I have seen those to, but remember that not all 3D printers are alike.

I have seen samples from 3D printers that were quite close to molded plastics. One of my previous clients used it for a low volume plastic tool that would have to flex a bit when used (click-on, click-off), not a single one ever broke.

Again it depends on the 3D printer technology. I have held examples in my hand that at best just useful to show the shape. But I have also held mock ups in my hand made were very close to the real thing.

Again it depends on the choice of technology.