Pretty much all DSLRs are plastic with some being built round metal chassis. Likewise CSCs. [ul]Modern plastics can be almost as strong as metal[/ul] and are pretty robust - not managed to break any yet!
From an engineering and pedantic view-point, there are many kinds' of 'strength'
Significantly, Tensile or how much force it can be pulled before it breaks; compressive or how much force can it be pushed by before it breaks, 'Bending' syrength is s dunction of the two; fatigue strength is how many times and how far you might bend the materisl before it breaks; and so it goes on....
And a materiallike metal, may be very very strong in compression, but hopelesss in fatigue... which is why skyscrapers have steel frames, but aeroplanes have hier wings replsaced at regular intervals.
AND, an awful lot of 'strength' is endowed NOT by the material, but the 'section' of the artifact.
Many 'plastic' and being a pedant,l lets qualify that as a yman made polymer, 'cos plastiv just means moldeable or maleabe, and warm or hot metal is actually plastic.... but many polymers, actually have 'strenghth' ratings higher than a lot of comon metals... they just remain 'plastic' and have a large degree of deformeable elasticity before they actually break.... and its actually that which we discern as making them 'feel' plastiky...
And in artifact, it can ironically be that 'plastic-ness' a certain amount of give before the structure actually breaks than makes the structure in a polymer stromher than in a metal.
EG: what's 'Stromnger' a 1" thick plate glass window, or an 8mm window made of perspex?
However.. here im lies answer to Badger's query. Its NOT the material that makes them feel cheap... they feel cheap cos they is cheap.... same applied to manual focus film camera lenses made of metal thirty plus years ago....
More expenbsive lenses will have a nicer 'feel' because they are made to a different grade, not necesserily 'cos they are made out of a more expsnsive material.
But generally, the more you pay the better they will feel. (Give or take the odd ecconomic anomoly!)