The Prusa i3 MK3 is one of FDM printers you can buy. Here's my printer with a bunch of mods to improve print quality and ease of use.
A quick link to a Thingiverse collection to some of mods featured here
Raspberry Pi W
Prusa MK3 Einsy RPi Zero Access
Allows access to the Raspberry Pi W for easier installations and removals.
Prusa MK3 X axis RPI Camera Mount
A camera mount for the official Raspberry Pi Camera that follows the print along the Z-axis.
Prusa i3 MK3 Raspberry Pi Zero Frame Remix
A little modification to the official Raspberry Pi Zero frame which allows the HDMI port to sit flush.
Prusa i3 MK2/MK3 External Ventilator Cover
Covers the extruder fan from blowing to the print surface and unintentionally cooling it/
Prusa MK3 Improved Shroud
This improved fan will allow the printer to do higher angles without requiring supports.
Filament Guide MK3
A super long filament guide that ensures the filament doesn't rub up against anything. To be used with https://www.thingiverse.com/thing:1940114.
Prusa MK3 Filament Sensor Cover Update
A better filament sensor cover which can be easier unscrewed using your fingers.
IKEA IVAR Filament Spool Holder
A spool holder I designed to fit nicely onto my IKEA IVAR shelf where my printer lives
Prusa Maintenance Stand
Great for when you need to work on the bottom of the printer (Y-axis). Recommended print
Prusa i3 MK3 LCD Screen Cover / Dust Cover
Covers the LCD screen so you can sleep or if you don't use the printer for a while
Prusa i3 MK3 Feet Smart Lock
Locks those rubber feat into place so they don't fall out when you slide or move the printer around
These axis improvements should be fixed on the new R2 parts released by Prusa. https://shop.prusa3d.com/forum/original-prusa-i3-mk3-f30/new-printed-parts-version-r2-b6-t14551.html
Prusa MK3 fixed Z mounts
These straighten up the Z-axis and also allow for easier maintenance. Better all-around.
X-axis improvement by RHDreambox
Has perfectly aligned my X-axis cables on the pulleys. Provides access to the cables too if required.
Y-axis improvement by RHDreambox
I am using the GT2 16T pulley variant which has improved the alignment of my cables. It's not perfect but close to it!
Bonus - TWICE Extruder indicator
As you may already know, I love TWICE. This indicator rotates as the extruder pushes and pulls filament. It's held on using magnets.