I ordered a bulkhead to connect CO2 tank to my fridge, but it's too short so I made an extension.

I tested it only with DMfit Bulhead Union 3/8" (ABU0606), but it should work on any M20x1.5 thread.

This model might not fit on the first try, it might require scaling the model a bit depending on filament used and your printer's accuracy. I myself scaled this model to 101.2%, because I printed it in ABS which shrinks a lot. Internal thread was a nightmare to get right, even with high tolerances, I only managed to screw it halfway down, but that's not a problem for me because it's perfect length for my fridge.

Specification

• Internal thread: M20x1.5
• External thread: M26x1.5
• Length: 37 mm
• Sides are cut to fit 24 mm spanner
• Nut is non standard, fits 30 mm spanner
• Washer OD is 32 mm