Gather Supplies:
+ Old flats (mine are leather)
+ Acrylic paint (for outline)
+ white Fabric paint
+ small Paint brush
.
... & most importantly
+ Drawing Skills!!

First, use the white Acrylic paint for outline drawing, because it washes off if you make a mistake. ;)
.
Right Shoe:
First paint the middle toe, down the middle of the shoe ...follow the curve of the shoe a little as well.
Theres 4 bones!

Then paint the next toe almost exact same way.
Then do the "big toe" ...which is shorter, & ONLY HAS 3 BONES!
.
...All other toes have 4 bones.

On the other side, draw the 4th toe. Same as first 2, just lil shorter (see in next pic).
.
**Use wet q-tip to fix mistakes!!**

& finish with 'pinky-toe'. Has thinner, & shorter bones.
.
& your finished sketchin the top!!
<<<--- Should look like this.

Now for the side:
.
Start near the heel; draw this shape (in pic). Its the heel/ankle bones.

Then draw 2 connecting square-shape bones.
Followed by a regular shape bone.
.
Make sure it looks like they fit together, like a puzzle piece. ;)

Once it looks good enough ...just trace over the whole thing in white 'Fabric paint'. This will make it permanent (even on slick surface shoes).
.
Be careful, bc it does not wipe off easily; stay in lines!!!

Let the right shoe dry ....
REPEAT PROCESS for left shoe (just toes r backwards now)!
.
Let dry over-night before wearing. Use wet q-tip to clean off any leftover acrylic off shoe.
.
And your done!
Show off your new X-Ray Shoes!