If you've got some welding and fabrication skills, sure you can make your own Wevo or Stomski coupler. But Hayden and Steven do the work for those who can't (or don't want to) and provide the steel ring sized to the transmission shift rod diameter, with tapped hole for cone-style set screw on one end, and on the other end is the splined shaft that fits into the shifter tube.
Those who can make their own? Grab a helicopter joint from Pegasus. Good people with most everything in stock.
https://www.pegasusautoracing.com/productselection.asp?Product=1490