The K40 laser cutter is quite a bargain (I paid £350 for mine), but you get what you paid for.
K40 Laser Cutter –
Chinese Laser Cutter K40 Upgrade
Cheap Chinese laser cutter upgrades
Tales Of A Cheap Chinese Laser Cutter
Laser Surgery: Expanding The Bed Of A Cheap Chinese Laser Cutter
Great for lighting up the laser engravers work area during setup.
K40 / Chinese Engraver 40w C02 Laser Cutter LED Upgrade
Motorized Z-Adjustable Bed for K40 Chinese Laser by SnowHead, Download free STL model
Simple Stuff Matters Everything as simple as possible, but not simpler
Story of the cheap Chinese K40 laser cutter engraver
K40 cutting bed modification : r/lasercutting
K40 Laser Conversion
3D printed Nema 23 mount
K40 Laser Cutter Upgrades
DGT-3000 Raspberry Pi Connector
K40 laser cutter bed upgrade - Way of Wood