Get your supplies
Using an X-acto knife, cut off the exterior bottom of the first cup (cutting around where the white base meets the real cup).
Detach the base and put it to the side. You'll need this later.
Grab your second cup and cut out the interior bottom of the cup.
The two cups should now fit together like so.
Take one cup and cut out a rectangular area the width and half the length of your upright phone.
Repeat step 7 on the second cup.
Attach cups at the bases and tape them together.
Put on your favourite song and slip you phone into the speakers, using the bottom of cup one as a support.