Noham Coupler

I've done the Dual Z upgrade, here is a straight coupler in replacement for the Oldham coupler. Similar to those Anodized blue aluminum couplers, but you print it yourself. Also, there are holes on the sides they measure 2.5mm you may need to drill them a bit bigger for the grub screws to go into. I'm not very good with holes and such, but I have a set of drill bits. I find that machine screws go into PLA without any issues, so some DIY is required.

This connects 5mm D shafts from 40mm stepper motors to an 8mm diameter lead screw.

It measures 15mm diameter, 22mm long.