Oxygen Tank Knob

Recently my wife started needing oxygen after she had the upper lobe of her right lung removed because of lung cancer. All is good now and the oxygen really helps her breathing. Portable bottles of oxygen come with a small "wrench" to turn on the O2 once connected to a pressure gauge.

However I found the included wrenches a pain to use as they're wobbly, flat, and extend out like a real wrench over 5 inches/13 cm. I much prefer knobs for situations like this so I modeled two that'll allow oxygen bottles to be opened with a knob instead of a wrench plus the room it takes up in a tank/bottle bag or backpack is much smaller.

One model has "Oxygen Knob" embossed on the top while the other top is blank.