This was initially based on the pattern supplied here, but as that did not work at all for me, I modified it heavily as I went. I also made it an all-in-one piece, instead of sewing the windows etc on later.
I used a 4mm hook, and this fits both an iPhone and iPod, and also (since I sized it to fit my phone) an LG Renoir.

4mm hook
deep blue yarn, (I used all 8ply, but you can resize accordingly)
black yarn
white yarn


Chain 31 in Blue yarn.
Row 1-15: Starting in second chain from hook, SC 30. Chain 1, turn

16: Make 5 SC in blue, 4sc in white, 1sc blue, 4sc white, 6 sc blue, 4sc in white, 1sc blue, 4sc white, 1sc blue, chain 1, turn
17: 1Sc blue, 4sc in white, 1sc blue, 4sc white, 6sc blue, 4sc in white, 1sc blue, 4sc white, 5sc blue, chain 1, turn
18: Make 5 SC in blue, 4sc in white, 1sc blue, 4sc white, 6 sc blue, 4sc in white, 1sc blue, 4sc white, 1sc blue, chain, 1 turn
19: 1Sc blue, 4sc in white, 1sc blue, 4sc white, 6sc blue, 4sc in white, 1sc blue, 4sc white, 5sc blue, chain 1, turn (Cut white, leave a small tail weave in as you do the next line in blue)

20-21: 30Sc in blue, chain 1, turn
21: 30Sc in blue, change colour to black in final stitch, before chaining up. Chain 2 in black
22: SC in second loop from hook, 30sc in FLO, chain 2, turn
23: SC in second loop from hook, 31SC in black, both loops, change colour to blue in final stitch, before chaining up. Don't chain up.
24: 30sc in BLO, finish off.


Light

Chain 4 in white yarn
Row 1-6: Starting in second chain from hook, SC 3. Chain 1, turn

Fold it down in half and sew to the top piece of the TARDIS

Directly opposite the light, attach a loop of white yarn long enough to hook over the light when your phone is in the cover, and attach firmly at the other side of the light. This way you don't need a separate button, and the closure doesn't detract from the tardisness of it all.