This is a tablet holder for bicycles on trainers. Primary goal for the design was ease of mounting. Only a few O rings or thick rubber bands are required for mounting on handlebars. Due to variances in design of handlebars and stems, this may not work for all combinations.
There is clearance for power connection in the bottom middle of the Pad Holder Base.

For securing this to the handlebar, I used Qty 2 of 220 size rings per side, its what I had lying around. Sizes you'll need will vary on the handlebar and stem size. There are three areas for O-Rings, two on the handlebar and one on the stem. I really needed just two on the handlebar, I didn't need one of the stem.

For hardware, you'll need Qty 4 thumb screws (1/4"-20 x 1"L) from McMaster Carr P/N 91185A925 and 4 nuts.

As a nice to have, I used Foam Tape from McMaster Carr P/N 8694K92. These are 1/8" thick by 1 1/2" wide which will fit the rectangular grooves on the base part. This just provides a soft surface for your tablet.

Print Qty 2 of Pad Holder Arm, 1 of other parts.