K40 40W CO2 Laser Cutter

Upgrades

reputable brand name 24V 2.1A 50W power supply:
$17.70 -- DigiKey -- Delta Electronics PMT-24V50W1AA

LightObject air assist head for the K40:
$22.00 -- 18mm Laser Head w/ Air Assisted. Ideal for K40 Machine

18mm diameter 2.0" focal length ZnSe CO2 laser lens, needed for the LightObject air assist head:
$29.45 -- TEH-HIGH Diam 18mm Focal Lens for CO2 Laser Cutting,FL:1.5" 2" 2.5" 3" 4" 5" 7.5"(2"/50.8mm) (1.5"/38.1mm) (2"/50.8mm)

5mm ID flexible tubing to connect the air assist head to the air pump:
$9.50 -- 5X8 Silicon Flex Tube for Air Assistance or Water Cooling(10ft)

diaphragm air pump:
$52.95 -- Active Aqua Commercial Air Pump, 8 Outlets, 60W, 70 L/min

this 158 GPH submersible water pump is the exact one we're using:
$18.52 -- EcoPlus 185 Fixed Flow Submersible/Inline Pump 158 GPH - 728300

I might go a size up though to be on the safe side, I feel like ours has on occasion lost it's siphon and not been able to push the water through the system to reestablish it, so maybe get the next size up from the same brand:
$23.00 -- EcoPlus 728310 Eco 396 Fixed Flow Submersible/Inline Pump 396 GPH

An adapter from the water pump's female port to a male barb to attach the hose:
Banjo HB050-025 $3.12 -- Polypropylene Hose Fitting, Adapter, 1/2" NPT Male x 1/4" Barbed

(future enhancement) air vent adapter:
$5.99 -- POWERTEC 70150 Rectangular Dust Hood for 4-Inch Hose