On Mon, 11 Apr 2011 11:26:15 -0700, Tim Wescott
wrote:

big snip
Ah -- that wouldn't work, and once again I'm confused in my terminology.
The application is very weight-sensitive: indoor rubber power
competition rules call out a seven gram minimum weight for this sort of
plane*, and that minimum is _very_ hard to build down to. I've got a
pair of wheels that look injection molded, but have about the same wall
width as most of the blow molded things I've seen. They weigh in at
600mg for the pair, while my wheels weigh in at less than 100mg each.

So what do you call molding with styrofoam beads?

* AFAIK, just about anything with wheels and a minimum weight calls out
7 grams -- 14 grams for outdoor.

I think vacuum forming might give you something useful for relatively
light weight. Heat up a sheet of something formable clamped in a
frame via IR (think toaster oven), pull it out, place it over two male
half molds, suck down. Cut out halves and glue together when cool.

On the other hand, it probably won't be as light as some rims bent up
and glued out of graphite prepreg tape, with graphite spokes and
graphite tube hub (maybe cure in the same toaster oven). If your
target complete model weight is 7 grams, anything molded will be
pretty heavy by comparison.

Pete Keillor