In the past I've only ever been 3D printing for the laboratory on a borrowed printer, but when I recently met someone who makes wonderful cosplay pieces, it really sparked my interest in using the technique to make cosplay props as well. I love seeing the wonderful creations people come up with, and love tinkering with the technology side of things.
My current project is a wearable Star Lord helmet from Guardians of the Galaxy, and all of his props for a cosplay. It's based around an excellent (and free!) model, which can be found here.
The printer i'm using is a refurbished Prusa i3 mk2s, which, while not the latest model (that would be the mk3s), does a very good job still and has proven a reliable workhorse. What I like most about this printer in particular is the large knowledge base available to me. Since it (and its successor) are such popular machines, you can find documentation on just about any issue you may run into during printing. There's also a very active Discord server where you can get live help troubleshooting and plenty of printable upgrades from Thingiverse.
The main downside to this printer is its limited build volume (250x210x200 mm). Especially when dealing with larger cosplay pieces, it may not be sufficient to print things in one piece. Since larger models aren't always broken up into smaller pieces, I would definitely recommend taking the time finding out how to break apart big models into print-ready pieces yourself if you're going for this type of printer for large objects. Software such as Slic3r allows you to easily do this (and is free!)
For this project I'm using ColorFabb's PLA / PHA blend filament, which prints beautifully on the mk2, and seems to be a bit sturdier than classic PLA. One downside to this material is that it smells a little during printing (shouldn't pose any problems in a ventilated room). It's also on the expensive side (~50 USD / kg). Something I wish I'd known ages ago is that it's actually recommended to print a 'temperature tower', to get a good idea of the temperature range where your filament produces the best quality prints. Especially with these hybrid filaments, starting off with that may save your skin in the future.
If, like me, you're quite new to these large prints, I recommend you check out frankly_built's video on angling prints, as this can save you lots of time (both in sanding and in printing), as well as material. If you're entirely new to 3D printing, there are numerous YouTube channels out there with introductory videos, which help to take your prints to the next level. One of my favourite channels is Maker's Muse, who has an entire series of videos focusing on new users.
As a personal suggestion: I made the mistake to print a large vertical piece with just a skirt instead of a raft (a skirt is a small outline around your print that is used to get the material flowing properly, while a raft is a strong base that will adhere your print to the printbed. More details on these and the third 'brim' option are available here.) Although my piece had support pillars, at around 80% through a 12-hour print, one of the pillars toppled over, resulting in all sorts of stringing on that part of the print. I definitely recommend using a raft for large vertical objects to ensure everything stays in place during printing.