This is a chemistry teaching aid, designed to be used to teach middle school students about electro chemistry, and the seperation of Hydrogen and Oxygen from H2O, when electricity is passed from an anode to a cathode in water.

This model was designed with a couple features that cannot be printed using a plastic 3D printer.

1. 2X M4 machine screws. Any screw will do, if you modify the hole size in the FreeCad file.
2. 14 Guage wire. The red and black colors are arbitrary, but help to demonstrate the function to students.
3. 1X Plastic Drinking Straw. 1/4 inch or 6mm straw is wheat was designed around, but this can be modified in the FreeCad file.
4. 1X Power Supply. If you have a printer, you have a power supply. This model will work with any voltage, but the higher the voltage you use, the faster the reaction occurs. This helps demonstrate the electrochemistry, if you have a variable voltage power supply. I used 9 volt batteries, as they can be daisy chanined into any factor of 9.

In order to build this:
#1 Attach the screws with wire around them, in order to form a watertight seal.
#2 Insert straw sections into the top, and use hot glue to make them stick. (Hot glue optional)
#3 Mix a cup of water with a teaspoon of baking powder or salt.
#4 Pour water into the hole. This is easiest accomplished by submerging the entire part in the water. Pour water into the tops of the straws, until it is as full as you can get it.
#5 Attach the wires to the battery.
#6 Notice how bubbles will come up from the chmber into the straws. If you cover the ends of the straws with your fingers, the water level in the negative side will lower at a rate faster than the positive side, demonstrating that the water is split into twice the amount of hydrogen as oxygen.
#7 Clean part after the print, simply pour water out, and flush with clean water. Set out until dry, and use again later!
#8 If reaction gets too slow, remove the machine screws and clean them off, oxidation on scres can slow down the reaction.

Print Cost = $2 (assuming $20/kg for filament)
Screws = $0.20 (If using stainless steel. cheaper if using non stainless, but oxidize the positive terminal instead of producing 02 gas.
Wire = $0.01
Straw = $0.02
Batteries = $1.12

Total Cost: $3.35

No commercial equivalent was found for this model.

Feel Free to Remix, try different materials, and let me know how you use this design!