TAILONZ PNEUMATIC Male Elbow 1/4 Inch Tube OD x 1/8 Inch NPT Thread 90 Push to Connect Fittings PL-1/4-N1 (Pack of 10)

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.