Casting resin.

[Kipper4]

Has anyone gotten any experience with casting resins.
I'm thinking of looking into casting some enclosures.
What to use?
Will it drill?

Go ahead make my day tell me it's possible.
Rich

[R.G.]

I've used casting resin for completely block-casting circuits for environmental hardening. You can cast practically anything that you can make a mold for. It's not hard, but like all technical processes, you have to set up correctly for it and follow some not-necessarily -obvious procedures. Pluss it's messy and smelly.

There are two classes of resins used in casting commonly. These are the polyesters and the epoxies. Epoxies are somewhat easier to work with, but are more expensive, so the majority of things labeled "casting resin" are polyesters. If it doesn't say "epoxy" it's not.  Polyesters work fine, but they require sealing from the atmosphere at the end of a pour. This is because exposure to air prevents the surface of the polyester from curing completely, leaving a permanently soft, sticky layer. The sealing is nost often done by pouring a very thin layer of polyvinyl alcohol (PVA) on the top surface of the polyester as a last step in the pouring process.

Both polyester and epoxies generate heat as they cure. This is a problem because it limits how thick you can make a single pour without endangering the encapsulated stuff (if any) or the resin itself from the generated heat. 1/4"/6.4mm is pretty doable without special issues. Note that only one dimension has to be this thin. I'm not sure how this works for deep, thin castings like pouring what amounts to a vertical wall, as in pouring something like a box. Probably it's OK In a metal mold, tricky in a thermally insulating mould.

Mold releases, stirring techniques, de-airing, cleanup solvents, gloves, ventilation, previous thought about dealing with spills, disposable shield clothing, eye protection, and other things like that are of course necessary for any chemical process.

Oh, and both kinds of casting resin are machinable.  Both can be colored with suitable pigments. For an eye-opener on what can be done with casting resins in the mechanical sense, visit a West Marine store's fiberglass repair section if you can. Both can have their mechanical properties after curing modified by addition of fillers. I like glass microspheres. 

[Kipper4]

Thanks for your time and expertise RG.
A few things I hadn't banked on there.
Maybe revise my ideas and thinking on this one then.

Rich

[R.G.]

Glad to help. Yell with more questions if needed.

[diffeq]

May I ask why casting resin? There are many plastic enclosures out there, made from sturdy ABS plastic, if you want lightweight. And other DIY methods too, not necessarily using polymers. Laser-cutting plywood and assembling a layered enclosure, for example. Stabilising it with epoxy will make it strong enough for dropping (such material was used as wings in early aircrafts). Speaking of ABS, there are sheets of it available. Can be heated and formed/folded.

[DIY Bass]

Another possible option for weird shapes would be 3D printing

[J0K3RX]

A bit impractical for obvious reasons but, I still think this is cool...

http://runawaybrainz.blogspot.com/2012/04/audio-crystal-cmoy-freeform-headphone.html

Thought about entirely encasing my wife's cell phone in this and making little holes for the speaker and charging port and slip it back into her purse. 

[anotherjim]

http://runawaybrainz.blogspot.com/2012/04/audio-crystal-cmoy-freeform-headphone.html
That's a wonderful idea. If it ever develops a fault you could easily see where it is. Oh, wait...
Looks really cool though. Great workmanship.