You didn't provide any information on production quantities or size/strength requiremetns.  This would be necessary for a good discussion.  It seems most of the plastic molding processes lend themselves to higher volume production, thus the expensive tooling.

In the meantime perhaps you may consider roto-molding as an alternative?  I saw that used to make kayaks once upon a time.  They poured powdered plastic pellets in a hollow kayak-shaped shell.  When heated, the plastic coated the inside of the mold.  It seemed the rotomold tooling for your "box" would certainly be much less expensive than injection molding tooling.  But that's a tricky process if my memory is still good.  One must determine the balance of heat transfer to material thickness through fins and sinks on the mold itself.

The September 2004 issue of Composites Fabrication magazine has an article about low volume closed molding processes and their comparative costs.  That may give you some hints or insights on other processes.  Maybe infusion?  Cheap, but tricky.

TygerDawg

We use a local plastics shop for hand fab for thsi kind of project.  They are very good at single to low volume production.  

tom  

     Sorry, answer wasn't complete.   It didn't sound like I addressed your question.

This is a huge issue for us as a very small manufacturer.   The very best answer is to work your tail off on the Internet and see how close you can come to a standard item.  In this case I would look for something simple where I could heat the top and mold it to shape.   Or I would do it backward and see what was available and see if I could make my design fit that.

The very best product is one you can build with entirely standard parts from dependable suppliers.   (Not clearance houses because once the material is gone, it is really gone.)   Put it in a unique configuration and figure out how to make part of it secret.  

Our filter systems are built from standard parts except for the frame.   www.carbideprocessors.com The secret part is the right combination of filters.   

tom      

Kydex is a plastic that is often used for simple mold forming.  Check at San Diego Plastics

http://www.sdplastics.com/

Kaydex is used for making knife sheaths-search the internet for "knife sheaths kydex."

Viper488,

I design plastic components and also work as a Manufacutuers Rep.  I did not see enough information in your post to point you in the right direction.

Although you should do a search on www.google.com
for "plastic boxes".  Their are many manufacturers out there that have stock plastic boxes.  You may find something that has already been tooled and you could avoid that expense.

If you are still stuck after doing a search, let me know.  One of my companies, specializes in  prototypes and short runs.

theanswerguy@tr-usa.com

Try looking for MUD (master unit and die?)bases. They are pre-manufactured mold pairs which take machined parts as inserts for the final product. There are restrictions in it, but this will get you started.

Hope this helps...

RikuY

Hi Viper,
Where are you located?
Depending on where you are geographically, I might be able to refer you to a molder which specializes in exactly what you are looking for.
Get back to me at burgoyne@sympatico.ca.

It could be worth trying model suppliers.
A friend of mine makes molds from a 2 part silicon type material, and molds things from a 2 part plastic compound.
Its very strong and can be mixed with iron or aluminium particles for different effects.
Our local supplier used it to repair a pot hole in his concrete floor, his fork truck drives over it daily!

A thermoform mold might also be an alternative. These can be built out of wood or resin for a couple thousand dollars, depending on size.
You might also call a prototyping firm and ask about a urethane mold.
Metro RP north of Indianapolis is a great shop.
www.metrorp.com
They produce urethane tooling that is good for a few parts.