Have you guys come across a product called 'Q Bond'? Basically it's plastic powder and superglue (cyanoacrylate) but it works incredibly well but don't try and substitute.
I've had incredible success on a range of plastics but mainly ABS. I use a rotary burr to grind a quarter inch wide channel about as deep as the material, back it with tape if needed, fill it progressively with the powder and wet it out with the glue, working progressively like your welding a thick piece of material.
The powder comes in two colours, grey and black, it dries quickly and can be filed, sanded.
Perhaps worth mucking around with? About 30 bucks for a kit
Cheers,
