Really?

There are some fundamental assumptions on your part about casting processes
and post casting processes that are incorrect.

Before I became a nobody camera guy -  I spent 13 years working in the
investment casting industry. Quality control, quotes, contracts, tooling,
machining, heat treating, non destructive testing, etc. making castings for
every possible industry you can image, nuclear, aerospace, automotive, oil,
etc. I wasn't a button pusher. I was management.

The part in question could be cast for less then .50 but quantities would
have to exceed 100,000, with no machining (important) which is conceivable.
Not that the part would sell for .50 mind you, we are talking cost.

We tooled up and produced about 2 million of the little fingers that hold on
the trac balls on lap tops, remember them from about 10 years ago? They came
in 3 sizes for about .30 each. Cast, heat treated, bent, machined, drilled
and tapped. The "apparatus" that did this, did so in 00:01:08. each.  The
Japanese competitor came to design with a plastic piece for about .15 each,
and it snapped and popped across the room at the show and tell. We won the
bid. We would have loved to sell this part for .75 or $1.25, and if we were
talking about making 5000 of them, we would have had not choice. But we were
competing with plastic and talking 2 million+. It was amazing how we did
this for .30 ea (with profit), and this type of technology happens all the
time. A big buyer like Canon talking 100,000's , could get this part tooled
up and produced in metal for much less then you might think, and, most
importantly, definitely not WAY more than plastic by default.

To your point, it would be bad if machining was required though, this would
drive up costs considerably. But the investment casting processes out there
today are remarkable. I know they are, (and you don't), because nobody gets
into an investment casting house unless you are an investment casting worker
or a casting buyer. There are no tourist tours. I don't intend to be
stand-off-ish about this, but most people don't see this stuff and you can't
just walk into an investment casting company for a tour. Extremely
confidential industry. The machine trades see a lot of castings and do a lot
of expensive work, which would drive costs up, but the investment casting
houses these days do more then just spit out little metal parts.

I would be hot water telling you what I am telling you about the lap top
fingers, but since the part is dead and long gone, who cares. Microsoft and
the investment casting company in question would NOT want this information
known 10 years ago.

Back to plastic - there are some extremely competitive and competent plastic
work out their. The part in question very well could be made in plastic and
work just fine. But, apparently the higher end camera's have this part in
metal and I am sure the Rebel isn't metal because they saved  - $50 -  per
camera. Maybe .10 or .30. Even a $1 isn't enough cost savings to offset
thousands of camera's coming back for warrantee repair, a repair of $1 part
or a $10 part or even a $20 part....who cares.... its the 2 hours labor that
kills the deal for Canon.....

Unless.....

the plastic part lasts *at least* one year.

Hymmmmm?

This plastic vs metal piece topic apparently is relatively new to the
newsgroup forum, and I am speculating that I may be the tip of an iceberg
here. The camera repair guys I talked to said it is starting to show up in
the tech talk. I bought the camera kind of early and used it hard. I either
got unlucky, or a whole bunch of people are going to start popping up with
this same problem. Time will tell. I am casting my vote for metal.

David A.

That the results I've got. I've used mine almost exclusively in tough, hot,
cold, and some rainy situations and not carried around in a nice padded
waterproof case. It's been banged and beaten (never dropped), and scratched
up plenty. Knock on wood it's still going strong and coming up on two years.
These results are not typical but I also have a 1D and all it took was one
good fall from the car seat to the road and I had to send it in for service.

I am not talking about the shutter mechanism, as in the shutter that opens
and closes over the sensor unit. Mine still works fine.

David A.