My Lulzbot Mini is VERY loud. What are some cheap ways I can make it quieter?
Hello. I’m assuming you’ve got a Mini1 since later Minis used a different main board (Einsy Rambo). Much of the noise is due to the drivers in the original Mini Rambo board (A4982) working through the stepper motors. The Einsy Rambo uses Trinamic TMC2130 stepper drivers that are much quieter.
More info here: MiniRambo - RepRap and here: EinsyRambo - RepRap
Lulzbot offers a newer, Einsy Retro replacement board that is designed as a drop in replacement for the MiniRambo.Einsy Retro Board 1.0 Retail
I have an early Mini 1 and have upgraded the stepper motors to MOONS rather than the original. These run a little quieter and don’t make the sing-songey, shrill sounds of the originals. Swapping out did take some work as the orignal steppers did not have connectors at the motors. The new steppers have worked reliably for the last 6 or 8 years. I purchased mine through Lulzbot; however, they now offer LDO steppers instead: NEMA 17 Stepper Motor, LDO - INCLUDING Adapter
Another upgrade that was popular is to add a flexible mounting plate between the stepper and it’s mounting point. These will also help dampen the noise and are available here: Amazon.com: Stepper Motor Vibration Damper, CNC 3D Printer Stepper Motor Vibration Damper for NEMA 17 Motor Reduce Noise and Vibration, 3D Printer Motors : Industrial & Scientific
or here: Moons' Nema 17 Stepper Motor Damper
I’ve considered replacing the original mainboard with an Einsy Rambo to quiet mine further and to gain an LCD and local control. It’s available through Lulzbot or directly through Ultimaker.
Hoping this helps.
Todd.
PS: Noisy steppers were a reality for most early 3D printers. We made the best of it like in this video: https://www.youtube.com/watch?v=FdIJuOCqU7U
There used to be GCode songs and notifications that were played through the steppers, usually at the end of a print. My how times have changed. 
Here’s an Instructable with a how to: Make Music With Stepper Motors! : 8 Steps - Instructables
Enjoy!