There are two main ‘flavors’ of plastics printing.
Type 1 is called “Filament” printers.
These use 1 kg (2.2 pound) (or smaller) rolls of meltable plastic filaments. 1.75 MM is the present standard. Which plastic? Well, there’s a long discussion that will have its own page one of these days.
The most common type is PLA – which is not hard to work with, but it’s soft and not food-safe. Then there is ABS (and other styrenes) which are stronger, so you may wish to install positive ventilation because of chemic al smells. There are also food-safe plastics in case the Dollar Store is too far and you just gotta print up some plastic dinnerware…
Other plastics may be pliable – like TPU, for example.
The filament of the chosen material enters a heated “extruder assembly” where it is melted in sequential “stacks” on previous layers. The lower end printers use a Bowden tube for feeing the filament while more pricey units employ “direct drives.”
Older (and cheaper!) printers can make some noise, but newer models are almost silent.
Example to look at on Amazon: Comgrow Creality Ender 3 3D Printer Aluminum DIY with Resume Print 220x220x250mm.
Type 2: These are called “Resin” printers.
They use a thin stream of UV-curing plastics (like what your dentist may use).
These will generally have a smaller build area, should be vented, and produce (depending on resin) harder plastics. Which means they also cost more for a given build area.
If you’ve ever had a filling at the dentist and he used a light-curing plastic (where there’s an ultra-violet light wand involved) you know the smell.
Thing is, the resin printers tend to result in smoother prints (with some adjusting). Because the during is not temperature-based. It’s light-based – so the layers tend to flow together more smoothly.
Unless you have a specific need for a resin printer, it may be easiest to start with a simple filament printer.