zjxed 1/2" OD x 1/4" OD Pneumatic quick Connector Push to Connect fittings Straight reducer Union/Coupler (Pack of 5)

For an air system, I would look into using pneumatic Push to Connect Fittings but these may not work for you concerning your arthritis. I use forstner drill bits to make the holes in the PVC pipe, the fittings are self tapping. Instead of PVC pipe, just use 1/2" pneumatic tubing for your main line, use 1/2" OD x 1/4" OD quick Connector Push to Connect fittings to connect your tanks. Note: PVC pipe is banned for compressed air use. Over time it will become brittle.