I made this at home after seeing that they are 15-20 dollars online and even more expensive at stores. I made it for around 6$ and had some of the stuff around the house. It worked perfectly for my compressor.
Step 1: Parts Needed
2- brass hose barbs (whatever size you need for air hose you're using)
1- brass coupler (same thread size as hose barbs)
1- pencil eraser
1- rounded thumb tack