Patrick, who sent along the DIY Roof Suction Bike Rack, sent along another hack that repurposes some bike parts into a nice little phone dock. Text and pictures credited to Patrick.
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Pretty easy hack, just take an old chain and cassette soak them in degreaser and rinse/ dry. Then I used a chain tool to wrap the largest and smallest cogs in the chain.
On the bottom you need to pick 4 spots to make the "feet" which is just 3 links of the chain large/small/large you attach the feet by pushing the pins down on the chain that wrapped the largest cog just make sure you don't push the two pins from the same link.
I had an extra cog from another cassette that I anchored on top using a paperclip pulled tight. The feet are optional but I put them on mine to allow me to pull and push the cable down as needed.