Revised Duct Tape Holder Bracket
Many thanks to jormakainen for his original bracket!
This remix is focused on (a) providing enclosed spaces to trap the rod; (b) accommodating a larger rod diameter (~23mm); and (c) making the overall bracket a bit larger and stronger.
To trap the rod, I found it helpful to install the top screw of each bracket, allowing them to swivel slightly to allow the rod to be inserted and captured.
I printed at 25% bicubic infill to provide extra strength -- feels like I could have probably gotten away with 18-20%.