First get an empty bottle and clean it well. I used this shampoo bottle for example.
Mark the section you want to cut and how high or deep the holder is going to be.
Do the same in the backside. Let big space for the connector part.
Cut the bottle following the marks with a good scissors.
Draw when the connector is going to be.
And cut it with the cutter.
Use fabric or paper to cover the holder and use a good glue. I prefer to use normal glue instead of silicone.
In less than an hou, you have your cellphone in the holder and there's no phone cords in the floor. Hope you liked it :) enjoy it!