have also scavenged some disposable bbq grillls
is fun making stuff!
for a trout, i'd be inclined to rig up a tripod/hanger like ray mears....they can fall apart
trying to think of a way to support the grill without it slipping down the pegs...suppose you could angle them at an ,er, angle.
tesco do a fish basket grill with a handle: reckon you could support that with a post and hook/tent peg arrangement.
had an exellent firebowl from an abandoned frying pan last year...found a saw, too, just lobbed in the bushes!
and for all you pyro's.... chipping might be boring, but burning is poisonous, ya wreckers!