Many 3D printers are made in China, and as asbestos is still legal in China (with large ongoing production it seems).
It is thus quite possible to end up with a 3D Printer that has asbestos parts in it.
Even though asbestos is illegal in some parts of the world (like Australia, though not the USA as far as I know), given the above, and the possible lack of care by suppliers and/or oversights during imports, one may want to do due diligence.
This becomes even more important if you plan to make modifications to your printer.
When speaking with even large producers, you may also get very conflicting answers ("yes part xyz has asbestos in it" vs "no it does not") - which further complicates the matter.
Asbestos testing is usually about 50-70 USD per sample, and often destruction of the tested item is necessary, so that is not a viable way either.
There are also heating elements used in printers which may be shielded with asbestos containing materials (as asbestos has good heat resistance properties).
How to avoid asbestos exposure with a high degree of certitude?