Above reference to SDS sections; last should read "16."
Michael's below recommendations are solid and 'have used all of them with success.
On plastic, fave is a mix half/half of Testors tube and liquid to make a slurry-consistency.
'Not fond of MEK (Methyl Ethyl Ketone) as it has an annoyingly high vapour pressure...toxic fumes and very runny.
Plastruct liquid solvent is useful at times but is sort of smelly...
...and with solvents in general, smelly is a "danger" signal.
For hidden areas, Gorilla Glue is good, however pay attention to the instructions, dampening the surfaces with water is important...
...and it expands somewhat. Also, scratch flat surfaces a bit with coarse abrasive paper (80 or 100) to give the glue more "bite" surface.
Beacon Gem-Tac is advertised as a Permanent Glue and is a "glorified white glue."
'Have not yet tried the light-curing glue but it sounds intriguing. anyone have experience there with?