Differences between ABS and PLA? Which is best?

[Sebastian Finke]

I would add a few things to this list:

The main differences are fairly simple.
pros:
1) abs is cheap and has good mechanical properties.
2) you can use acetone to make it smooth and pretty.
3) it can be cold-welded

cons:
1) unless printed in a fully heated enclosure - warps like a bastard.
2) you pretty much end up breathing in a lot of acetone fumes. Only at temperatures exceeding 400C!
3) makes your workshop smell like burning plastic It doesn't smell as pleasant as PLA, granted, but certainly not like burning plastic.
4) can be tricky to make stick to print surfaces. Absolutely not true

pla.
Pros:
1) very easy to print with, warping varies from none to a tiny amount.
2) will stick to just about any print surface
3) so many types around that there will be one that does what you want it to
4) good general prupose pla is cheap.
50 no real smell when printing. Actually I think it smells great.

cons:
1) specialist pla filaments can be pricey, although flexible pla is cheaper than tpu (polyurethane based) flexible filaments and much much easier to use
2) cannot be cold-welded.

The point is that abs is a long standing plastic that was developed for injection moulding. Whereas todays pla filaments have been specifically developed just for 3d printing.

This is absolutely untrue. PLA has been around since the 1930's (if I recall correctly it was developed by DuPont in 1932) and is used extensively in injection moulding particularly in the food packaging industry (yoghurt tubs, etc) and also disposable cutlery and plates (like camping gear).