OpenDive retrofit rubber band holders
thingiverse
If you use the original OpenDive design, here are some square tabs (yea, I know, amazing engineering....) that you can put in place with abs cement, or superglue for PLA, that replace the plastic rods. You can then use Rubber Bands to hold your phone in place.
Download Model from thingiverse
With this file you will be able to print OpenDive retrofit rubber band holders with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on OpenDive retrofit rubber band holders.